In patients with post partum endometritis once daily intramuscular administration of gentamicin may be convenient in certain clinical settings. However pharmacokinetic data on once daily intramuscular gentamicin are not reported. In this study 10 women with post partum endometritis were given once daily intravenous gentamicin (4 mg/kg ideal body weight) followed at a later day by a similar intramuscular dose. Gentamicin levels coincided at 30 min. Levels at 60 and 90 min were lower with the intravenous route. Further clinical studies are needed to confirm reduced nephrotoxicity and ototxicity with the intramuscular route.