Background:  The aim of the present study was to investigate whether a combination of rofecoxib and gabapentin could improve pain relief and reduce opioid requirements, compared with rofecoxib alone, during the first 5 days after tonsillectomy. Methods:  In a randomized, double‐blind, placebo‐controlled study, 49 patients received gabapentin 1200 mg pre‐operatively, followed by gabapentin 2 × 600 mg on the day of operation and gabapentin 3 × 600 mg for the next 5 days, or placebo. Both groups were given rofecoxib 50 mg daily. In the post‐operative care unit, intravenous morphine was administered in doses of 2.5 mg on request. From 4 h to 5 days post‐operatively, ketobemidone was offered as escape drug. Pain at rest and during swallowing, and side‐effects, were assessed using a four‐point verbal rating scale. Results:  As a result of the global withdrawal of rofecoxib, the study had to be terminated prematurely. This report comprises the results from 22 patients in the gabapentin group and 27 patients in the placebo group. Gabapentin reduced ketobemidone requirements during the first 24 h post‐operatively 4.5 mg (standard deviation, 3.0 mg) in the placebo group vs. 2.0 mg (standard deviation, 2.0 mg) in the gabapentin group; P < 0.003. Gabapentin induced more dizziness (P < 0.002), gait disturbance (P < 0.02) and vomiting (P < 0.05) during days 0–5 than placebo. No other statistically significant differences were observed. Conclusion:  Gabapentin reduced opioid requirements in the first 24 h after tonsillectomy. The benefits of the reduced opioid intake may be overshadowed by the drawbacks of side‐effects.