The goal of this study was to evaluate the efficacy of single- and multi-dose (5-day) clindamycin therapy for the prevention of inflammatory complications in patients undergoing lower third molar surgical extraction with bone removal. Patients who qualified for the prospective, randomized, double-masked, placebo-controlled trial were randomly divided into three groups: (1) single dose of oral clindamycin administered preoperatively (single-dose group); (2) clindamycin administered preoperatively with continued therapy for 5 days (5-day group); and (3) a placebo group. The following parameters were evaluated on the first, second and seventh days postsurgery: trismus, facial swelling, body temperature, lymphadenopathy, alveolar osteitis and subjective pain sensations. There were 86 patients (31 in the single-dose group, 28 in the 5-day group and 27 in the placebo group) enrolled in the study. There were no statistically significant differences in postoperative inflammatory complications in patients during the first and second days postsurgery. A statistically significant variation in body temperature was reported on the seventh day. Analysis of the postoperative analgesic intake did not show statistically significant differences between examined groups. Clindamycin applied in a single preoperative dose of 600 mg with or without subsequent 5-day therapy does not demonstrate efficacy in prophylaxis for postoperative inflammatory complications after third molar surgery.