Aim: The aim of this study to evaluate the role of yolk sac diameter as a predictor of pregnancy outcome. Materials and Methods: The research was conducted at the Department of Obstetrics and Gynecology, with clearance from the institute’s ethical committee. 150 pregnant women of gestational age 6-10weeks were included in this study. The trial excluded patients with molar pregnancy, ectopic pregnancy, multiple gestations, uterine anomalies, women ith known endocrine disorders. Results: Out of total 117 cases in good outcome, 91.5% had a normal yolk sac diameter and 8.5% had an abnormal yolk sac diameter at first visit. Out of total 33 cases in poor outcome, 12.1% were found to have a normal yolk sac diameter and 87.9% were found to have an abnormal yolk sac diameter at first visit (P value <0.001). This study found that the sensitivity of normal yolk sac diameter for predicting good outcome is 91.45% and the specificity that abnormal diameter of yolk sac predicts poor outcome is 87.88%. Conclusion: Greater yolk sac diameter had a poorer outcome compared to cases with normal yolk sac diameter, missed abortion being the most common adverse finding. Yolk sac shape and size assessment gives a good overview of pregnancy outcome in first trimester. Hence, it is advised that yolk sac biometry be done routinely in first trimester.