A prospective double-blind study was performed to compare metoclopramide (Primperan) with morphatropin in the treatment of ureteral colic. Twenty-one patients (10 in the morphatropin group and 11 in the metoclopramide group) entered the study and diagnosis was confirmed radiologically. Using the Mann-Whitney rank sum test, no significant difference was found in the pain-relieving effect 10, 20, or 30 min after treatment with either 1 ml morphatropin s.c. or 20 mg metoclopramide i.v. Two patients in the morphatropin group developed nausea and giddiness, respectively, and 1 patient from this group was omitted due to the development of urticaria. No side effects occurred in the metoclopramide group. Thus metoclopramide seems to be an alternative to the traditional treatment of ureteral colic with morphia.