Abstract. Full-text article is available at: https://arxiv.org/abs/1410.0533Quality of service in cellular communication system is a topic that recently has raised much interest for many researchers. This paper presents the findings obtained from the study on factors affecting QoS in Tanzania cellular networks. The study was carried out in Dodoma Municipal, Tanzania. The study employed cross sectional research design. Information was gathered from structured questionnaire of 240 subscribers during the study of quality of service for the four leading cellular networks in Tanzania. Both qualitative and quantitative data from field survey were collected and analyzed using Statistical Package for Social Sciences and Excel software. The study findings show that the major factors that degrade QoS in Tanzania cellular networks are inadequate network infrastructure, lack of fairness from service providers and little efforts taken by the government in enforcing the national agreed standards. Other factors are lack of reliable end to end systems, geographical terrain, low quality handsets, poor government monitoring on standards and lack of subscriber skills and training.