Background:Perineal tear is a very common complication of vaginal delivery, and it is often mild. However, when severe, it could result in torrential life threatening hemorrhage and anal sphincter injury, with fecal incontinence. Objective: The objective of this study is to determine the predictors of severe perineal tear (3rd and 4th degree tear), using mild perineal tear (1st and 2nd degree) as control. It would also determine the rate of perineal tear, and the maternal and fetal demographic risk factor associated with it. Materials and Methods: This was an analytic observational study of 186 women who had perineal tear during vaginal delivery. Out of these, 19 women had severe (3rd and 4th degree) perineal tear, also known as obstetrics anal sphincter injury (OASI). This was compared to 167 women who had mild perineal tear (1st and 2nd degree) during the study period. Maternal demographic information retrieved was maternal age, parity, educational level, and occupation. Obstetrics factors were booking status, gestational age at delivery, mode of delivery, rank of the accoucheur (nurse or doctor), and degree of perineal tear. Fetal demographic data was birth weight and fetal sex. Categorical variables were compared with odds ratio, difference in mean was compared with student’s t-test, and the degree of association for quantitative variables was determined using Pearson’s correlation coefficient. Predictor variables were determined using simple logistic regression, and multivariate analysis. Confidence interval was set at 95%, and statistical significance was set at p value of < 0.05. Results: The prevalence of OASI (3rd and 4th degree perineal tear) in Yenagoa was 1.1%. The significant risk factors were women of younger age, odds ratio = 1.04(0.37, 2.87) with p = 0.04, low parity, odds ratio = 0.20(0.07, 0.55) with p = 0.008, low educational background, odd ratio = 18.9(5.92, 60.81), and birth weight ≥ 4kg, odds ratio = 0.30[0.09, 1.06] with p = 0.04. Using simple liner regression, the most significant predictors for severe perineal tear were mode delivery (r2 = 65.5%), and educational level (r2 = 30.0%). However, on stepwise multivariate analysis, these two factors accounted for 68.5%. Conclusion: The rate of severe perineal tear is relatively low in Yenagoa, Nigeria, and comparable to what obtains in many countries. The most significant predictors were mode of delivery and educational level. Careful selection of the mode of delivery, especially instrumental vaginal deliveries, and women empowerment could minimize the rate in our environment.