The purpose of this investigation was to determine the meal pattern that characterizes the increased food intake of the ob/ob mouse. The major result was that obese mice ate larger and less frequent meals than lean mice during the dark phase of the light-dark cycle. There was a sex difference in that obese females ate the largest meals. To investigate the possibility that the different meal patterns observed in obese and lean mice was an artifact of the temporal criterion used to define a minimal intermeal interval, the meal patterns of obese and lean male mice were analyzed using two temporal criteria, 1 min and 5 min, and a behavioral criterion, the behavioral sequence of satiety. This analysis demonstrated that obese mice ate larger meals than lean mice whenever the criterion for an intermeal interval included the behavioral sequence of satiety. The mechanisms responsible for the increased meal size in obese mice are not known, but we suggest that preabsorptive satiety mechanisms may be less potent in obese mice.