INTRODUCTION. Nicotine replacement therapies (NRT) are effective for smoking cessation. After having received over-the-counter (OTC) status in Germany, concerns grew about effectiveness, increased risks, especially of adverse cardiovascular reactions, and inappropriate use of NRT. Thus, a pharmacy-based cohort study was launched. OBJECTIVES. To assess effectiveness, safety and appropriateness of use of an OTC nicotine patch (Nicotinell, Novartis Ltd.). Every customer who bought an OTC Nicotinell patch was eligible. All data were collected by self-administered questionnaires at weeks 2, 4, 8, 12 and 24 after inclusion. Six hundred and thirty-three customers were admitted, median duration of smoking was 19 years. Of the participants, 6% smoked up to 10 cigarettes per day, 43.6% between 11 and 20, 34.3% between 21 and 30, and 16.1% more than 30 cigarettes. Twenty-four weeks later, 351 participants replied: 28% (177 of 633) had quit smoking completely. Considering replies only the proportion of complete responders raised to 50.4%. There were no serious adverse events reported; 62.9% complied with the directions for use and did not use the patch for more than 3 months. About 45% smoked simultaneously with NRT. Pharmacy-based cohort studies are feasible. This study indicates that the nicotine patch is effective and safe in an OTC setting. There is still room to improve compliance with the directions for use.