In a general practitioner intervention against smoking (employing nicotine chewing gum) smokers who used more than a box of gum were, prior to the intervention, more motivated to quit smoking and more dependent than those who did not use more than a box. They were also older. Even after controlling for demographic, dependence, motivational and previous success factors, those who used more than a box of gum had a significantly enhanced probability of success compared with other smokers. Although causal conclusions cannot be drawn from these analyses, stress on the importance of persistence in use of the gum is recommended.