Dissertation (MMed Obstetrics and Gynecology)Background: A functioning maternal referral system is critical in preventing adverse maternal and fetal outcome. Integration of emergency obstetric care with maternal referral system are strategies of reducing maternal and perinatal mortality in Tanzania, but still there is high number of maternal and perinatal mortality especially in referral cases. So it was important to find out factors which determine adverse obstetric outcome in referral patients. Objective: This study was carried out to assess the referral diagnosis and determinants of obstetric outcomes of emergency obstetric referrals at Iringa Regional Referral Hospital. Methodology and materials: This was hospital based cross sectional study. A purposive sampling technique was employed and involved all referral women with obstetric emergency referred at the hospital during the study duration. Structured pretested questionnaire was used to collect data on socio-demographic characteristics, obstetric history, diagnosis and maternal/fetal outcomes. Data were analyzed using SPSS version 20. Descriptive statistics were generated and associations of categorical variables were examined in bivariate analysis. Odds ratio and 95% CI was used as a measure of association. P value of< 0.05 was considered significant. Results: A total of 231 obstetric emergency referrals were recruited in the study. 224 referred women delivered during the study period and 7 were managed and discharged before delivery. The most common referral diagnoses were prolonged/obstructed labour (35.9%), fetal complications (18.1%) and hypertensive disorders in pregnant (11.7%). Absence of operating theatre was the main reason for referral (43.3%), followed by needs of expert management (30.7%). Maternal outcome revealed that 5.2% of all emergency obstetric referrals experienced post partum haemorrhage. Perinatal death was 14.7%. A logistic regression analysis revealed that women delayed to arrive at IRRH were more likely to have adverse maternal outcome (AOR 6.13, 95% CI 1.40-26.71) and adverse fetal outcome (AOR 3.40, 95% CI 1.41-8.18). Conclusion: Prolonged/obstructed labour was the common referral diagnosis. Absence of operating theatre, need of expert management and lack of blood transfusion service are the most reasons for emergency obstetric referral to IRRH. Timely referral will prevent most of maternal and neonatal adverse outcome.