The Danish Amputation Register and the nationwide National Patient Register are presented. Based upon the code numbers in the WHO classification system (ICD), 4 etiology groups i.e. vascular insufficiency, diabetes mellitus, malignant neoplasma and trauma were extracted. The purpose was to analyse the relationship between level of amputation (i.e. foot, below-knee, through-knee, above-knee and hip) and etiology (cause of amputation). The material represents all such amputations in Denmark during the period 1978 to 1989 (n = 25.767). The number of amputations because of vascular insufficiency with and without diabetes mellitus decreased over the period studied. The number of tumour and trauma amputations seemed unchanged. There was a significant reduction in the number of amputations at proximal levels (above-knee) for vascular insufficiency with and without diabetes mellitus and in the trauma group. No such change was found regarding tumour amputations. There was a characteristic pattern in the distribution of level respectively of etiological factors for each etiology group and for each level of amputation.