A metaanalysis was done to identify the most effective prophylactic antibiotic regimen in hip fracture surgery. Specific comparisons addressed were antibiotics at any dose versus placebo, multiple doses (>24 hours coverage) versus one dose of antibiotics, and multiple doses versus 24 hours antibiotic coverage. Outcomes measured included overall wound infections, deep wound infection, superficial wound infection, urinary tract infection, and mortality. A computer search of the Medline and EMBASE databases (English language literature from 1966 to 2000 and 1988 to 2000, respectively) retrieved 15 randomized controlled trials which addressed the specific aims. Most studies evaluated antibiotics from the cephalosporin group. Antibiotic prophylaxis significantly reduced overall wound infections when compared with placebo and was equally effective for deep and superficial infections. One dose of intravenous antibiotics seemed no different than multiple doses. Antibiotic use also was associated with a significant reduction in the incidence of urinary tract infection but had no significant effect on mortality.