We have studied the volume of water which should accompany diazepam 10 mg oral premedication given 1-2 h before induction of anaesthesia in 75 patients undergoing elective gynaecological laparoscopy. Twenty-five patients were given 20 ml (group A), 25 patients 150 ml (group B), and 25 patients 300-450 ml of water (group C). There were no differences between the groups in gastric fluid volume and acidity. All groups reported a reduction in thirst and dryness of the mouth after water intake, while only group B reported significant anxiolysis. Eight patients in group C experienced augmented diuresis, compared with no patients in groups A and B. We conclude that 150 ml is the ideal amount of water given with oral premedication 1-2 h before anaesthesia.