The occurrence of an acute superficial phle bitis in a patient with hemophilia A is reported. The patient is a 29-year-old hemophiliac who was hospitalized because of a severe posttraumatic left knee hemarthrosis.The phlebitic changes involved the left basilic vein and appeared after 9 days of hospital stay, while the knee condition had already considerably improved. No changes in the underlying coagulation defect were present at the time of the onset of the phlebitis. During the hospital stay, besides fresh or frozen plasma, the patient was given i.v. analgesic therapy namely Novalgin, a pyrazolon derivative, and Tal-win, pentazocine lactate. It is assumed that the phlebitic changes were secondary to the administration of the compounds. The process disappeared in 3 days with no therapy.