OBJECTIVE To review our experiences with diagnosis and management of symptomatic ureteral calculi complicating pregnancy. METHODS Medical records of all pregnant patients documented with symptomatic ureteral calculi treated at the Division of Urology, Department of Surgery, Faculty of Medicine, Ramathibodi Hospital from 1990 to 2000 were reviewed. Presenting symptoms, diagnostic studies and management of ureteral stone were evaluated. RESULTS Twenty patients were found in this study with the mean age of 27.5 years (18-36). The mean gestational age at presentation was 18.5 weeks (12-33). Severe flank pain was the common presenting symptom (100%), 60 per cent were on the right side and 40 per cent were on the left side, 20 per cent had associated fever and 20 per cent had irritative voiding symptoms. All of the cases had micro or macroscopic hematuria. Ultrasonography was the initial test confirming the diagnosis and visualized stones were obtained in 60 per cent of the cases. Plain KUB film was done in 6 cases and stones could be seen in 5 cases (83%). Limited IVP was done in 3 cases and the diagnosis could be done in all of them (100%). Spontaneous passing of stones was noted in 14 cases (70%) and double J stents were placed in 6 cases. Ureterolithotomy was done in 2 cases and percutaneous nephrostomy with subsequent definite stone treatment in the post partum period was done in 2 cases. No abortion and no congenital anomalies of the infant were noted. Four cases had premature labor but there was no correlation with the procedures performed for treating the ureteral stone. CONCLUSIONS This study provides evidence for effectiveness of diagnosis and treatment of ureteral stone during pregnancy. The appropriate management may be helpful to reduce morbidity of urinary calculi during pregnancy.