Smoking cessation leads to weight gain but the reason for this gain is not clearly established. The objective of this study was to compare the mean change in dietary intake among quitters and non-quitters enrolled in a smoking cessation program. Mean dietary intake was measured using 24-hour recall over the telephone at baseline and 6 weeks after the scheduled 'quit date'. Baseline data were obtained from 177 subjects and 130 (73%) were recontacted with complete data. There were 47 quitters (27%). The mean self-reported weight gain among the quitters and non-quitters was 2.4 kg +/- 3.1 and 0.04 kg +/- 2.5 respectively (p = 0.001). Mean energy intake was the same at baseline between the quitters and non-quitters. There were statistically significant changes in dietary intake between quitters and non-quitters. Given the high within-individual variability (sd 832) this sample size was only sufficient to detect differences in the change in intake of approximately 460 kcals between quitters and non-quitters.