The frequency of pulmonary embolism was investigated in a 10-year period from 1971 to 1982. During this time approximately 30 000 operations in 60 000 surgical and medical patients were performed. In seven patients, six boys and one girl, pulmonary embolism was diagnosed. This includes six patients with septic embolism, arising in three cases from subacute endocarditis, in two from osteomyelitis of the humerus and in one from coxitis. Only in one patient, a boy who was operated for perforated appendicitis, pulmonary embolism resulted as a complication of left-sided ileofemoral thrombosis. In three boys with osteomyelitis and coxitis, staph. aureus was found locally as well as in blood culture and in sputum. Prophylactic anticoagulation is recommended by the authors in all children over 10 years who were immobilized due to a septic process.