Two hundred and ninety-eight cigarette smokers attended the first session of the Five Day Plan to Stop Smoking; 201 of them also attended the fifth session. Of the latter group, 146 (72.6%) had not smoked a cigarette during the preceding 24 hours. Ten weeks after the plan, 287 of the 298 original participants were contacted by telephone: 84 (29.4%) had not smoked a cigarette during the preceding seven days. Ten months after the plan, 49 participants from a previously selected subgroup of 50 who attended the first and fifth sessions were contacted by telephone: 41 were still smoking cigarettes but eight (16%) had not smoked a cigarette since the plan ended. The "therapeutic success" rate of the plan (discontinuance of cigarette smoking ten months after the plan) was 16%.