Eighty patients undergoing routine standardised extracapsular cataract surgery with lens implantation were divided randomly into two groups in a prospective double blind study comparing effects of preoperative norfloxacin eyedrops with placebo on bacterial contamination of anterior chamber aspirates after surgery. Pathogenic organisms were identified from 19 (24%) of the aspirates. The most commonly isolated organisms were coagulase negative Staphylococcus species. There was no statistical difference between the norfloxacin treated and placebo groups. This study demonstrates that routine use of topical preoperative antibiotics to eliminate the entry of bacteria into the eye during surgery is debatable.