Periodic health examinations are an excellent opportunity to counsel smokers to quit. The impact of a specialized smoking cessation counselor on the smoking behavior of patients having periodic health examinations was studied in a general internal medicine practice. One hundred fifty-five smokers having periodic health examinations were randomly assigned to a control group who received usual physician advice or an intervention group who received usual physician advice and two counseling sessions with a smoking cessation counselor. The two groups were similar in all demographic variables, smoking-related baseline variables, and baseline levels of motivation and intention to quit smoking. The smoking status of 97% of the subjects was assessed 6 months later. In the intervention group, 46% made quit attempts and 19% quit, compared with 34% and 12%, respectively, in the control group. Intervention-group smokers made more quit attempts (mean +/- SD, 5.0 +/- 2.5 vs 1.8 +/- 0.2) and had a greater reduction in daily cigarette use (8.4 +/- 1.5 vs 3.5 +/- 1.3). Of the 74% of smokers with higher levels of motivation to quit smoking, more intervention-group smokers attempted to quit (70.8% vs 45.5%) and succeeded in quitting at the 6-month follow-up (27.1% vs 10.9%). Periodic health examinations are an excellent opportunity to counsel smokers to quit, especially those smokers with higher levels of motivation to quit smoking.