ObjectiveTo compare the postoperative results from use of antibiotic prophylaxis for one and five days among patients undergoing lumbar arthrodesis at up to three levels.MethodsForty-three patients who all underwent lumbar arthrodesis due to degenerative disc disease at one, two or three levels were evaluated. They were divided randomly into two groups: one received antibiotic prophylaxis with cefalotin (1 g) and the other received the same antibiotic for five days. After the surgical intervention, the patients were evaluated at the time of hospital discharge, at the first return to the clinic (two weeks later) and 90 days after the date of the surgery with the surgical wound, with clinical examination of the surgical wound and laboratory tests on both groups.ResultsIt was observed that among the patients in the group with one day of antibiotic prophylaxis, 28.6% presented complications in the surgical wound, while in the group with five days, 27.9% presented complications.ConclusionThis study demonstrates that a single dose of antibiotic prophylaxis is as effective as a regimen of multiple doses in lumbar arthrodesis surgery at up to three levels. Thus, the costs and risks of subjecting patients to hospitalization under a prolonged drug regimen are unjustifiable.