Indwelling venous catheters were responsible for 19 of 44 hospital-acquired septicemias. The catheter was in place an average of 5.2 days and was associated with phlebitis or infected wounds or both in 18 cases (95%). Etiologic agents were Staphylococcus aureus, 13; gramnegative bacilli, 5; and a nonpathogenic yeast. Neither associated diseases (12) nor inappropriate diagnosis (12) nor treatment (9) influenced survival (17 [89%]), provided the catheter was removed. Both related deaths were due to S aureus; endocarditis was a complication in one. The septicemia rate for the 756 patients with catheters in place more than 48 hours was 2.5%. House physicians maintained 10% of the total catheters but were responsible for 17 (89%) of the related septicemias. We recommend daily observation of the catheter and immediate removal from phlebitic sites.