In a retrospective study (by questionnaire) of 8032 personnel exposed to anaesthetic gases in operating and recovery rooms in Ontario hospitals, and 2525 non-exposed hospital staff, the response was 78.8% for the exposed and 87.2% for the unexposed personnel during the period 1981-5. Logistic regression analysis, with age and smoking standardised, showed that women in the exposed group had significantly increased frequencies of spontaneous abortion and their children had significantly more congenital abnormalities (p less than 0.05). No chronic disease was significantly associated with the exposed group. These findings, together with similar ones from other studies, suggest that it is prudent to minimise exposure to waste anaesthetic gases.