Interpersonal conflict is a research topic increasingly gaining importance in project management. The purpose of this exploratory study was to find out how relationship conflict affects task conflict in projects. The research investigated the styles individuals prefer to handle task conflict with colleagues in bad personal relationship. The influence of four personal characteristic variables (Gender, Age, Work experience and Culture background) on the choice of conflict handling styles were examined at the same time. ROCI-II was used as the data collection instrument. Questionnaires were published through web-based online survey system. 182 valid responses were collected in two weeks. Data was analyzed with statistic software SPSS. The results revealed that integrating, compromising, avoiding, dominating and obliging are the five styles ranked from highest to lowest preferred by individuals to handle task conflicts with colleagues in bad personal relationships. High value of assertiveness and negative value of cooperativeness indicated that in a situation of relationship conflict, individuals are more assertive and less cooperative to deal with task conflicts with colleagues. Results of the study didn't show significant difference among personal characteristic groups. High correlations among conflict handling styles were discovered from this study. Implications of the research findings for theoretical and practical organizations or individuals are provided. Areas and recommendations for future research are suggested.