The aim of this prospective randomized study was to evaluate the effect of using a rubber drain on postoperative pain, swelling and trismus after lower third molar surgery. Of 100 patients with impacted lower third molars referred for surgical extraction, there were 40 males and 60 females, aged 18-40 years (mean=26+/-6.2SD). The patients were randomly divided into two equal groups. In the experimental group, a Penrose rubber drain was inserted into the extraction socket near the buccal fold after surgery and left for 72 h. The control group was selected using the same criteria and treated under the same surgical protocol as the experimental group, but without use of a rubber drain. Pain, swelling and trismus were evaluated at 24h, 72 h and 5 days postoperatively in both groups. The results of the study indicate that the use of a rubber drain reduces postoperative discomfort in the form of swelling and trismus after lower third molar surgery, but seems to have no effect on pain.