We evaluated the prevalence of infrequent voiders syndrome (defined as women with a mean voided volume above 400 ml) and predisposing factors among the female nursing staff in a busy 100 beds department of surgery. One hundred and five nurses and assistant nurses were invited to fill in a questionnaire and a frequency/volume chart for a 24-hour period. The infrequent voiders were further studied using uroflowmetry and medium-fill CO2 cystometry. Seventy-two women completed the study. Six (95% c.l. 3%-17%) were infrequent voiders, although fifty women (57%-80%) suppressed the desire to void during working hours. Main reasons for suppression of desire to void were busy work, poor toilet facilities and indolence. The frequency of micturition was higher during evening and night shifts than in the day shift. In the infrequent voiders the functional bladder capacity ranged from 550-1,100 ml, but none had residual urine exceeding 120 ml.