The effect of helium-neon (He-Ne) laser on the prevention of pain, swelling and trismus following the removal of an impacted third molar was studied in 100 patients randomly allocated to receive He-Ne laser, ibuprofen or placebo in a prospective double-blind parallel clinical trial. Trismus was significantly reduced in the He-Ne laser and ibuprofen treatment groups. Pain was significantly less in the ibuprofen group with regard to He-Ne laser and placebo groups. Swelling was the same in the three treatment groups.