An extreme heat wave in August 2003 had caused thousands of deaths all over Europe. Suitable prevention measures were demanded. The heat-associated mortality in Frankfurt on the Main, Germany, in summer 2003 is here analysed and published. Material and methods: Death certificates issued in Frankfurt from June V to August 31 It 2003 were checked with regard to sex, age, domestic situation and diagnosis. Mortality was compared to the daily temperature (mean, maximum, minimum temperature), measured online in Frankfurt by the Hessische Landesamt fur Umwelt und Geologie. Results: In August 2003 there had been a heat wave in Europe with extreme temperatures. In Frankfurt, Germany, from 3(rd), to 12(th) August, maximum temperatures were constantly exceeding 35 degrees C, minimum temperatures being constantly above 21 degrees C. The death certificates of 1,487 deceased were analysed, 656 men and 831 women. In June, mortality was 44/day with a maximum of 21 /day. From August 6(th) onwards daily mortality increased sharply to a maximum of 51 /day on August 13(th). Mean daily mortality in August increased to 20.4/d, with regard to the first half of August up to 27.6/d. Excess mortality during this heat wave in Frankfurt was about 200 persons, about 100 living in old-age pensioners homes and about 100 living in their private homes. Excess mortality increased with age: compared to mean mortality in June/July 2003, in the first half of August excess in mortality was 66% for persons 60 - 70 years old, 100% for persons 70 - 80 year old, 128% in the age group 80 - 90 years and 146% in persons more than 90 years old. Discussion: Our data demonstrate that there is a high risk of excess mortality among the elderly population during heat waves, also in Germany. Persons living in old-age pensioners homes are at risk as well as persons living in their private homes. Therefore prevention must be prepared by the public health services not only for those living in nursing homes but for those living in private homes as well.