Plaster of Paris is an effective ancillary treatment in the surgery of infected cavities in bone. It is well tolerated and spontaneously absorbed over a period of weeks to months, being replaced by bone of normal architecture. It effectively obliterates much of the dead space, leaving little room for hematoma formation. It would appear logical to treat local infection, especially involving rigid walled cavities, by a locally diffused antibiotic. When incorporated into plaster of Paris pellets, two antibiotics, Fucidin and gentamicin, are capable of prolonged local release in bacteriocidal concentrations. On the basis of in vitro observations on bacterial cultures, it is proposed that antibiotic-plaster of Paris pellets might be a simple adjuvant technique to good surgical debridement in the treatment of bone infection. Plaster of Paris has the practical advantage over acrylic cement beads containing antibiotics in that it is resorbed and would not need a subsequent operation to be moved.