OBJECTIVE To assess the pain and swelling during the first week after surgical extraction of impacted mandibular third molars and the relationship with oral hygiene and smoking before surgery and during the postoperative period. METHODS A prospective study was performed on patients undergoing surgical extractions of impacted mandibular third molars. Pain was recorded on a visual analog scale from 1 to 10 and swelling on a 4-point descriptive scale at 2, 6, and 12 hours after surgery and daily during the first postoperative week. Oral hygiene and smoking before surgery and during the postoperative period were recorded. Statistical analysis was performed of all the variables. A P value less than .05 was considered statistically significant. RESULTS A total of 50 patients (27 men and 23 women) with a mean age of 26.3 years (range 18 to 39) underwent surgical extraction of an impacted third molar. The maximum pain occurred during the first day and the maximum swelling at 24 hours after surgery. The patients with a lower brushing frequency before surgery reported greater pain. Likewise, the patients who smoked more after surgery experienced greater pain at 24 hours postoperatively. The hygiene after surgery and smoking before the surgical intervention had no statistically significant relationship to the occurrence of pain (P > .05). Swelling had no relationship with the variables studied (P > .05). CONCLUSIONS Surgical extraction of an impacted third molar caused moderate pain and swelling during the first 24 hours after surgery. A lower brushing frequency before surgery and during the first postoperative week as well as smoking after surgery were related to greater pain scores.