The success of international business depends on effective negotiations. Such negotiations do no happen in a vacuum, but usually in a specific environment that includes; time, surrounding, place, culture and people. The business environmental setting includes legal and political pluralism, currency fluctuations, foreign exchange, foreign government controls, bureaucracy, instability, change, ideological and cultural differences, as well as the influence of external stakeholders. These business negotiations environments can influence the behaviour of negotiation in global firms, impacting firms internationally. The reasons to negotiate on an international level may include considerations such as: choice of venue, culture to observe; and the outcome of the negotiation process. The aim of this study was to determine the influence of the international marketing environment, awareness of negotiation skill, interest groups and negotiation atmosphere on behaviour of marketers in a global firm. The study assessed the impact of negotiation behaviour on business agreements based on trust and certainty and level of commitment. The purpose of the study was to gauge the impact of negotiations behaviour pertaining to failure of business negotiations in Tanzania. In addition, the study endeavoured to determine the impact of environmental variables on the negotiation behaviour of marketers. The questionnaires used in the study comprised seven variables with statements linked to a five-point Likert-type interval scale varying from “strongly agree” to “strongly disagree. Self-administered questionnaires were used for data collection from global firms’ marketers and their management representatives; 323 questionnaires were collected from respondents. This study contributed to the literature on negotiation behaviour in a global firm and the perceptions of such global marketers in Tanzania. Many international companies in Tanzania find it difficult to formulate and implement a comprehensive business strategy; therefore, this study intends to equip international business managers with the leadership skills required. Based on the findings of this study, the negotiators and government are expected to play a major role in business negotiations to promote effective trade agreements despite limitations of political influence in the negotiation process. Political stability in a country enhances foreign business which in turn improves negotiation behaviour. A just legal system, with clear and unambiguous business guidelines and policies would benefit and promote local businesses and government representatives and negotiators in respect of international business negotiation behaviour. Reasonable tax and interest rates and fair business policies should improve international trade negotiations and business practices. In order to conduct successful international negotiations aspects such as culture, language differences, customs and traditions are important and should enjoy high priority. Aspects such as these mentioned influence the conducting and atmosphere and outcome of negotiations. The study reveals that the use of specialists and interpreters are imperative to guarantee understanding and successful outcomes. According to the findings negotiators should possess good negotiating skills to be able to steer the negotiation process through the different phases of negotiation that requires different negotiating skills at each stage of negotiation. It is clear that to have successful win-win negotiation outcomes the leading negotiator should put together a good team, with expert knowledge of product or conditions and negotiating skill, as well as possessing the attributes mentioned in the previous paragraph. The negotiator should also be able to determine authority limits, patience and observe negotiation ethics. No team disagreements concerning the business/project matters should be aired in front of counterparts during negotiations and professional conduct must prevail at all times. The findings of the study indicated that awareness of the practice of offering concessions regarding government tariff laws and price discounts that is in line with traditions in Tanzania. Concessions should not be made until all issues have been discussed, to avoid granting unnecessary benefits during negotiation that might be interpreted as bribery. This study concluded that it is important that marketers meet the requirements of business practices by sharing clear guidelines and policies regarding business practices, as this will lead to fruitful decisions. It was also found that negotiation behaviour improves when negotiators are willing to share information and agree that all communication must be in writing; marketers are more comfortable when there is a clear understanding of matters agreed upon, the choice of trading partners and that all trading agreements are written and a contract signed by all the parties, including governments where necessary. Marketers’ intentions are derived from the common interests of both parties and the negotiations should always take place in avenue that is suitable to both parties, conducted in fairness and offers must be reasonable and attainable with a positive outcome as the ultimate aim for both parties. This study reveals that negotiators insist on the use an agent or agents and sub-contractors to ensure mutually beneficial strategic business partnerships. However, when the role of the interest groups is explained to all participants, negotiation behaviour improves. It can also be concluded that negotiators allow interest groups to participate as team leaders and their number should be equal to the number of foreign negotiators, to ensure that marketers feel more at ease and comfortable to participate. An atmosphere based on bargaining power exerts a positive influence on the level of commitment among negotiating partners; and can be a predictor of the range of agreement as well as shape limits and priorities among dimensions of rivalry. However, it is important for marketers to express willingness to accept the terms of their counterpart’s bargaining zone regardless of non-profitable quotas at stake; identify areas of bargaining from foreign traders even if they are not attractive enough for local traders and are comfortable with the counterparts’ bargaining zone regarding fixed rates on exporting and importing quotas between trading partners to build trust among negotiators. In conclusion, it was found that negotiation behaviour has a positive influence on the level of commitment of trading partners. A positive business relationship is created on trust and a high-level of commitment which should be of great satisfaction to negotiating parties for future prospective negotiations.