Introduction: Perinatal mortality is one of the indicators used to measure the health status of women, newborns and the quality of health provided during antenatal and perinatal period. In Tanzania, Neonatal mortality has remained high (26/ 1000 live births) and it is estimated that more than 1.6 million babies are born every year of which 51,000 die within the first 28days of life. The objective of this study was to determine the causes and factors associated with perinatal deaths among women delivering in the three municipal hospitals in Dar es Salaam, Tanzania. Materials and methods:The study employed an unmatched case control study design and was conducted between November 2010 and February 2011. A pretested and structured data abstraction tool was used to collect information from labour ward registers and the antenatal cards of mothers of the study participants. Data was entered into the computer, cleaned and analyzed using EPI INFO 3.5.1 software. Bivariate analysis was done using the Chi-square test and multiple logistic regression was used to determine the variables which are independent predictors of perinatal mortality. Results: A total of 600 babies (200 cases and 400 controls) were included in the study. Major causes of perinatal mortality included prolonged/ obstructed labour (22%), preeclampsia/ eclampsia (23%), and prematurity accounting for 18.5% of the perinatal deaths. Mothers of the cases were more likely to have a history of previous adverse pregnancy outcome (AOR 2.35,, hypertensive disorder (AOR, 6.67, 95%CI=3.55-12.64), and premature delivery (AOR 12.18,. Conclusion: Pre-eclampsia/ eclampsia, prolonged/ obstructed labour, and prematurity were found to be the main causes of perinatal mortality. Hypertension during pregnancy, a history of previous adverse pregnancy outcome and prematurity, were significantly associated with increased risk of perinatal death. We recommend active screening for risk factors during ANC and timely management of hypertension and obstructed/ prolonged labour.