Local delivery of antibiotics by a degradable carrier has the potential for high local antibiotic levels and avoids systemic toxicity. Intravenous access, renal function monitoring, and subsequent surgical removal may not be required when degradable local delivery modalities are used. This study examined the in vivo elution of gentamicin from processed bovine collagen (type I) in 66 adult White rabbits. Collagen impregnated with gentamicin (3 mg/kg) was implanted into the vastus lateralis, and data were collected from 15 minutes to 28 days after implantation. Local tissue biopsies were taken a minimum of 2 mm from the implantation site. The gentamicin was released into the local tissue and averaged more than 3,800 micrograms/ml during the initial 4 hours after implantation. Local levels fell to 6.90 +/- 5.22 micrograms/ml at 24 hours and subsequently were 2.70 +/- 1.75 micrograms/ml or more through day 28. Serum levels reached an average peak of 4.04 +/- 1.75 micrograms/ml at 5 hours after implantation, decreased after the initial 24 hours, and subsequently were less than 0.41 +/- 0.20 microgram/ml through day 28. Collagen impregnated with gentamicin proved to be an effective degradable carrier of gentamicin in the healthy rabbit; it provided local tissue concentrations above the minimum inhibitory concentration and serum concentrations below levels associated with systemic toxicity for 28 days after implantation.