A retrospective study is presented of 14 patients with pathologic fractures of the humerus (12 established, two impending) treated with Seidel nailing from 1988 through 1995 in the authors' institution. There were nine women and five men whose average age was 59.5 years. Breast, prostate, and kidney hypernephroma accounted for the majority of the primary lesions. All but one lesion were located in the middle shaft of the humerus. Ten lesions were considered large (> 5 cm long). In five cases an open curettage and allografting were done. Early pain relief was successful in 85% of the patients. The worst complication found was definite nerve palsy in two (14.28%) patients. Ten fractures healed and two failed to heal. Two thirds of the patients had good functional results. The average survival was 12 months. Intramedullary fixation of pathologic fractures improves the quality of life by controlling pain for most patients.