OBJECTIVE To describe the characteristics of nighttime urinary incontinence in a sample of nursing home (NH) residents. METHODS Prospective descriptive study of a convenience sample of incontinent NH residents. METHODS Four NHs. METHODS 136 incontinent NH residents. METHODS Frequency and volume of incontinent and continent voids for three 10-hour daytime and three 10-hour nighttime data collection periods. RESULTS The frequency of nighttime incontinence was the same as during the day, but the volume of nighttime incontinent voids and total nighttime volume were higher than during the day. There was substantial between- and within-subject variability in volumes, but the distribution of ratios of night/total volumes approximated a normal curve. Diuretic use was associated with relatively low nighttime volumes. CONCLUSIONS About one-quarter of the NH residents we studied produced substantially more urine at night than during the day. Several medical, behavioral, and environmental approaches should be considered for reducing the frequency and volume of nighttime incontinence in this population.