OBJECTIVE Surgery is an essential part of treatment for tumors of the salivary gland, yet there is increasing evidence in the literature supporting the necessity of adjuvant radiation therapy. The patients described in this report were selected to receive postoperative radiation therapy because they were found to have positive margins. We have reviewed their records to identify factors influencing the control of local disease, the development of distant metastases and overall survival, and to define the role of postoperative radiation therapy in patients with positive surgical margins. METHODS A total of 17 patients with malignant tumors originating from the major salivary glands seen between 1970 and 1988 who were treated with surgery and postoperative radiation therapy were reviewed. All patients had positive surgical margins. RESULTS Overall local control at five years was 65%. Classified by T-stage, local control was obtained in all two patients for T1 disease, in five of six for T2, in four of six for T3, and in none of three for T4. At five years, the ratio of patients free of distant metastases was two of two for T1 lesion, four of six for T2, three of six for T3, and none of three for T4. Five-year survival was obtained in all eight patients with T1 and T2 lesions, four of six for T3, and one of three for T4. Patients with neck nodal metastases present in the neck at admission did worse than those with negative nodes, with 0% (none of three patients) free of locoregional recurrence vs. 71% (eleven of 14), 0% (none of three) free of distant metastases vs. 63% (nine of 14), and 0% (none of three) survival at five years vs. 93% (13 of 14). CONCLUSIONS Postoperative radiation therapy for patients with positive surgical margins was effective for T1 and T2 disease. However, patients with T3 and T4 disease require more aggressive therapy. Patients with nodal metastases in the neck at admission tended to have distant metastases and had poor prognoses. Further therapeutic measures using adjuvant chemotherapy might be explored for these patients. Patients with adenoid cystic carcinoma with positive surgical margins tended to have perineural invasion and distant metastases. However, the utility of chemotherapy for patients of adenoid cystic carcinoma with distant metastases remains uncertain, because effective drugs for adenoid cystic carcinoma do not exist and patients live for several years without chemotherapy.