Objective To assess the feasibility of the application of International Classification of Diseases-10—to perinatal mortality (ICD-PM) in a busy low-income referral hospital and determine the timing and causes of perinatal deaths, and associated maternal conditions. Design Prospective application of ICD-PM. Setting Referral hospital of Mnazi Mmoja Hospital, Zanzibar, United Republic of Tanzania. Population Stillbirths and neonatal deaths with a birth weight above 1000 grams born between October 16^th 2017 to May 31^st 2018. Methods Clinical information and an adapted WHO ICD-PM interactive excel-based system were used to capture and classify the deaths according to timing, causes and associated maternal complications. Descriptive analysis was performed. Main outcome measures Timing and causes of perinatal mortality and their associated maternal conditions. Results There were 661 perinatal deaths of which 248 (37.5%) were neonatal deaths and 413 (62.5%) stillbirths. Of the stillbirths, 128 (31%) occurred antepartum, 129 (31%) intrapartum and for 156 (38%) the timing was unknown. Half (n = 64/128) of the antepartum stillbirths were unexplained. Two-thirds (67%, n = 87/129) of intrapartum stillbirths followed acute intrapartum events, and 30% (39/129) were unexplained. Of the neonatal deaths, 40% died after complications of intrapartum events. Conclusion Problems of documentation, lack of perinatal death audits, capacity for investigations, and guidelines for the unambiguous objective assignment of timing and primary causes of death are major threats for accurate determination of timing and specific primary causes of perinatal deaths.