Background and problems: ​In a market with increased competitiveness, it's important for companies to achieve superior performance. Thus by being quick at meeting new market conditions and customer needs. To achieve superiority, kaizen is a suitable tool to use. The kaizen-philosophy comprises to constantly make improvements in everyday work and require commitment from all parties in a company. Some improvements work advantageously occasionally while others give good and long lasting effects. It may be difficult for organizations to maintain the results of kaizen improvements and the effects may diminish some time after implementation. Generally for companies that work according to the philosophy is that some improvements are implemented without adequate guidance and resources. This results in frustration since the improvements do not remain successful. Whether a kaizen-improvement implementation is successful has many influencing factors. In order to investigate this problem, Scania has been studied in regard of the company's good experience in applying the kaizen-philosophy. Previous research and literature have been investigated in order to support and analyze the topic. Thus, this study's research question is "What factors affect success and survival in implementation of a kaizen-improvement?". 5 Purpose:​ The purpose with this case study is to create a profound understanding of underlying factors which are critical for implementing kaizen-improvements and its further survival. Thus to understand what characterizes an successful implementation of kaizen-improvements. By successful kaizen improvement is meant an improvement that is standardized and becomes a beneficial part of the company. Method: ​This thesis is based on a qualitative research strategy. The research design is a single case study with semi-structured interviews as a method for the empirical material that has been collected. Conclusion: ​In the implementation process ten successfactors were identified in three different areas where Scania experienced difficulties with kaizen. In the first area, difficulties were due to cheating in the preparation stage. Here, the following successfactors were identified: An accurate and favourable current situation analysis, communication of the current situation and a good competence assessment. The second area was due to difficulties in implementing new working methods. Here, the following successfactors were identified: Communication of goals, employee training and favourable follow-up. The last area was due to difficulties in motivation employees. Here, the following successfactors were identified: Commitment and participation, responsibility, avoiding guilt and good leadership.