Objective: Evaluating the effect of perineal length on the duration of the second stage of labor, the mode of delivery, the need for episiotomy and the possibility of perineal and vaginal tears needing repair. Participants and Methods: It is a prospective hospital-based observational study done on 483 parturient women in a university hospital. Personal, medical and obstetric data together with the measurement of perineal length were recorded in the first stage of labor. We followed up the progress of labor until delivery. Regression models were used to consider possible risk factors of episiotomy or tears needed repair. Results: The mean duration of the second stage of labor was significantly longer among women with a perineum of ≥4 cm length when compared with those with a perineal length of <4 cm (36.7 ± 13.05 vs. 26.9 ± 10.4 minutes; respectively). Regression analysis of possible risk factors showed that circumcised primigravida with long perineum (≥ 4 cm) are more liable to have episiotomy (OR (95%CI) 1.96 (1.1 -3.5); 20.9 (11.1 -39.5); 4.8 (2.5 -9.2); respectively). Tears needed to repair are however, more common in circumcised women with short perineum (<4 cm) who delivered without episiotomy (OR (95%CI) 14.16 (8.1 -24.9); 4.54 (1.5 -14) respectively. Conclusion: Longer perineum is associated with increase in the duration of the second stage of labor. Obstetricians should expect the need of episiotomy when confronted with circumcised primigravida with long perineum. However, if the perineum is short they should not be deceived, short perineum is more probably torn.