ObjectiveTo determine postoperative surgical site infection (SSI) rates in three separate patient groups who underwent orbital surgery without prophylactic systemic antibiotics.Study designSingle-centre retrospective descriptive case series.Study populationWe studied the notes of 639 consecutive patients who had undergone orbital surgery in our hospital from 2009 through 2013. All patients belonged to either of three groups: (1) clean orbital surgery (n=226); (2) clean orbital surgery with implant (n=290); (3) clean-contaminated surgery (n=92). Thirty-one patients were excluded.ResultsOf the total of 608 patients, without systemic antibiotic prophylaxis, only five were diagnosed with SSI 5/608 (0.82%): 1/226 in the ‘clean’ group, 3/290 in the ‘clean-with-implant’ group and 1/92 in the ‘clean-contaminated’ group. All five patients with SSI were effectively treated with antibiotics.ConclusionIn this study ‘clean’, ‘clean-with-implant’ and ‘clean-contaminated’ orbital surgery was safely performed without prophylactic antibiotics. Where postoperative infection did occur, the patients were effectively treated with systemic antibiotics. We suggest to restrict the administration of systemic antibiotic prophylaxis in orbital surgery.