Background: Puerperal sepsis is the major cause of maternal morbidity and mortality worldwide. About 94% of maternal mortality occur in low and middle-income countries including Tanzania. Objective: To estimate the prevalence, document factors and causes of puerperal sepsis among postnatal women who attended postnatal care in Kilimanjaro Christian Medical Centre Hospital in the year 2015. Methodology: A descriptive cross-sectional study was carried out at Kilimanjaro Christian Medical Centre, Tanzania. A total of 183 medical records of attendance in 2015 were used for the study. Information about the isolated organism in culture was retrieved from the Laboratory Information System. Results: The prevalence of puerperal sepsis was 11.5% (21/183). The most common factors and causes of puerperal sepsis included caesarean section 66.7% (14/21), postpartum haemorrhage 57.1% (12/21), moderate to severe anaemia 61.9% (13/21), prolonged labour 76.2% (16/21) and bacterial infection 90.5% (19/21). The difference was significant at p<.05. The most bacteria species isolated among women with puerperal sepsis was Staphylococcus spp 50.0% (7/14), Escherichia 28.6% (4/14) and Streptococcus spp 21.4% (3/14). Conclusion: Puerperal sepsis is prevalent (11.5%) at Kilimanjaro Christian Medical Centre. Staphylococcus spp was found to be a predominant isolate which causes puerperal sepsis followed by E. coli and Streptococcus spp.