In a double-blind, randomized, comparative study, 101 atients subjected to natural events like insect bites or solar erythemas were treated locally with either dimethindene (DIM) gel (n=49) or placebo (PLA) gel (n=52). Mosquito bites were the most frequent incidents. Efficacy assessment was based on the speed of disappearance of itching. When only the first event is taken into account, 43 out of 49 patients (88%) treated with DIM were relieved from itching within 30 min of the gel application. The corresponding figures for PLA were 33/52 (64$) (p=<0.01). For all events (n=226) the results gave 85/101 (84%) cases relieved for DIM and 82/125 (66%) for PLA (p=<0.01). Only minor and transient side-effects were notified in either group. In these everyday life conditions, DIM gel was shown to relieve ruritus more quickly than PLA, especially in mosquito-bitten patients.