The radio-opaque marker technique (ROMT) is a safe and noninvasive method to determine total colonic (TCTT) and segmental colonic transit times (SCTT). Previous results have shown that smoking volunteers had significantly longer TCTT than nonsmokers, but the underlying mechanism was not clear. We investigated the effect of transdermal nicotine application in two different doses in a nonblind randomized experiment involving three distinct phases. In phase 1 baseline transit times were determined with an abdominal X-ray after a 6-day period of marker ingestion and again after the following bowel movement to study the influence of a bowel movement just before the X-ray. TCTT was nearly twice as high before than after defaecation (42.6 h vs. 25.1 h, P < 0.05). The main acceleration was found in the rectosigmoid (RS) (18.6 h vs 7.1 h, P < 0.05) with no significant changes in right (RC) and left colon (LC). In phase 2 and 3 nicotine was applied in two doses of 17.5 mg day−1 and 35 mg day−1 in random order. Both doses resulted in a significant decrease of TCTT compared to the predefaecation baseline (42.6 h vs 32.2 h/28.2 h, respectively, P < 0.05). Again the main effect was located in the RS (18.6 h vs 9.9 h/7.6 h, P < 0.05). Short-term application nicotine results in a decrease of TCTT which is due to an accelerated transit in the RS.