The demand for blood donations has been increasing due to the rapid population growth observed from the country to global levels. However, empirical evidences have shown that there is a shortage of blood donation rate in developing countries where by 35 out of 43 countries in Africa do not collect enough blood to meet the requirements. The evaluation presents the design and findings on the implementation process of blood donor retention strategies at Eastern Zone Blood Transfusion Services. The evaluation report aimed to evaluate: awareness and knowledge on strategies used to retain blood donors, how the blood donor retention strategies were implemented and the challenges encountered during the implementation process. A case study design under qualitative method was conducted in Ilala municipality in Dar es Salaam region. A formative approach evaluation was used to assess the ongoing blood donor retention strategies. Data were obtained from in-depth interviews and focus group discussions with 34 respondents who were selected purposely. The process of data analysis started with preparation and organization of data, followed by, reviewing of transcripts and then categories and patterns were generated and finally data was presented. Also Atlas.ti software was used to analyze data and findings were presented using a narrative approach. Specifically this involved extensive illustrative quotations. The evaluation findings showed that participants have adequate knowledge and awareness towards the strategies employed to retain blood donors. Also findings showed that organization activities did not achieve its goals due to lack of supervision, monitoring and evaluation. In addition the findings showed that inadequate funds and human resources have affected the performance of blood donor retention strategies implementation. The evaluation study concluded that retention of blood donors strategies was not effectively implemented due to acute shortage of resources support its implementation. Hence, it was recommended that, the government through the Ministry of Health and Social Welfare should take responsibility of ensuring adequate financial support to the blood transfusion services. There is a need to increase supply of enough qualified human resources to manage and run the blood donor retention programmes, working tools and the availability of guidelines documents.