From 1 January 1986 to 30 June 1989, 15 pregnant women were diagnosed as having urolithiasis. Patients presented in the last two trimesters with an infection of the lower part of the urinary tract (60 per cent), flank and abdominal pain (27 per cent) and hematuria (13 per cent). Ultrasonographic findings confirmed the diagnosis in 47 per cent of the patients. Other roentgenologic procedures were required in the remaining patients. Initially, therapy was conservative in all, and in 67 per cent of patients, no further intervention was necessary. Only 33 per cent required invasive measures; cystoscopic passage of an internal ureteral stent was the initial procedure of choice at our institution. Three of five patients who underwent invasive procedures had surgical intervention for relief of ureteral obstruction. Intensive care management was necessary for one of these three patients who had acute hemorrhage occur during the procedure. These data emphasize the need for the accurate diagnosis of urolithiasis during pregnancy. Ultrasonography was a valuable diagnostic technique, but a limited excretory urogram is safe and appropriate when there is uncertainty. Conservative management (hydration, analgesia and antibiotics as indicated) of obstructive uropathy was successful in the majority of instances. A specific clinical algorithm facilitated the successful management of patients necessitating operative intervention. Optimal management requires clinical suspicion and a precise diagnostic and therapeutic plan.