For four representative hospitals, emergency room contacts were registered during 1988, 1989 and 1990. A total of 2,935 of these contacts were due to insect stings, equivalent to approximately 9,000 p.a. in the whole of Denmark. For insect sting allergics and for others with severe reactions to insect stings it is important to realize that stings can occur during whole year and during day as well as at night. However, 59% were stung in July or in August and 46% between 3 and 9 p.m. Stings on head or hands were most common. Only 2% required admission and only 5% were controlled in out-patient clinics or by doctors outside hospitals. This means that surprisingly few patients were referred for allergy testing and possibly immunotherapy.