A new case of oxytocin-induced water intoxication is reported in a 30 year old gravid woman. The severe symptoms of this uncommon complication are principally neurological; biological signs are a hyponatraemia with low plasma osmolality. Usually, biological and clinical signs are rapidly cleared up by treatment, but maternal death or neonatal water intoxication may occur. Such accidents must be prevented by clinical monitoring, watching out for alarm signals (oliguria is always found, resulting from the effect of oxytocin on the kidney), minimum fluid and proportional salt intakes, careful monitoring of oxytocin infusion rates, facilitated by the use of a constant flow-rate pump.