The use of prophylactic antibiotics to reduce postoperative complications in third molar surgery remains controversial. The study was a prospective, randomized, double blind, placebo-controlled clinical trial. 100 patients were randomly assigned to two groups. Each patient acted as their own control using the split-mouth technique. Two unilateral impacted third molars were removed under antibiotic cover and the other two were removed without antibiotic cover. The first group received antibiotics on the first surgical visit. On the second surgical visit (after 3 weeks), placebo capsules were given or vice versa. The second group received antibiotics with continued therapy for 2 days on the first surgical visit and on the second surgical visit (after 3 weeks) placebo capsules were given or vice versa. Pain, swelling, infection, trismus and temperature were recorded on days 3, 7 and 14 after surgery. Of 380 impactions, 6 sockets (2%) became infected. There was no statistically significant difference in the infection rate, pain, swelling, trismus, and temperature between the two groups (p>0.05). Results of the study showed that prophylactic antibiotics did not have a statistically significant effect on postoperative infections in third molar surgery and should not be routinely administered when third molars are removed in non-immunocompromised patients.