The purpose of this study was to determine the postnatal outcome of renal pelvis dilatation that is detected in fetus by antenatal ultrasound scanning. Material and methods: This single-centered, retrospective study was conducted over a 24-month period from January 2017 to December 2019 including 52 pregnant patients. Fetuses with an anteroposterior pelvic diameter of ≥4 mm in the second trimester and/or ≥7 mm in the third trimester were enrolled. The fetuses were allocated to three groups based on pelvic anteroposterior diameter (APD) detected on ultrasound: APDs of <10 mm, 10–15 mm and >15 mm were classified as group 1, group 2 and group 3 respectively. Patient’s characteristics, postnatal pathology and postnatal management over a period of 2 years were discussed. Results: Among the 52 infants whose cases were followed, 22(42.30%) had APD of <10mm, 18(34.61%) had APD of 10–15 mm and 12(23.07%) had APD of >15 mm respectively. Mean maternal age in the study population was 31.32±2.71 years. Among the affected fetuses, 34(65.38%) were delivered as male and 18(34.61%) were female. Left sided renal pelvis dilatation was seen more common than right, with about 29 fetuses (55.76%) having left pyelactasis. Bilateral renal pelvis dilatation was seen in 12 (23.07%) fetuses. Postnatally, transitional hydronephrosis was seen in 18(34.61%) infants, pelvic uretero junction obstruction in 18 (34.61%) infants, vesicouretric reflux in 13(25%) infants, and posterior urethral valve in 3(5.76%) infants respectively. Out of 22 infants with APD of <10mm, 20 resolved itself during followup of 2 years. Out of 18 infants with APD of 10-15mm, none of them resolved in 2 year follow up, 5 required surgery and 13 were still under followup and were given antibiotic prophylaxis. Of the 12 infants with APD >15mm, none of them resolved in followup of 2 years while 7 required surgery in 2years whereas 5 were still under followup and antibiotic prophylaxis. Conclusion: Totally, 38.46% of pyelectasis detected on antenatal ultrasound scanning resolved spontaneously in 2 years followup. The magnitude of fetal renal pyelectasis correlated with postnatal outcome, as 90.90 %( 20 out of 22) infants resolved in 2 years followup in group 1(APD<10mm) while none of the infant resolved in group 3 (APD>15mm). Also, 58.33 % (7 out of 12) infants in group 3 required surgery in course of management while none required surgery in group1 over period of followup