A retrospective analysis of 34 cases of sino-nasal squamous cell or undifferentiated carcinoma in patients admitted between 1984 and 1992 was undertaken. Multimodality therapy incorporated radiation, surgery and chemotherapy. The five-year survival rate was 53 per cent. The local control rate was 82 per cent. Patients died of local failure (six), distant metastases (six), lymph node metastases (one) and other causes (three). Twenty-eight patients with local control were separated into groups: G1–2 (well and moderately differentiated) and G3–4 (poorly differentiated and undifferentiated) and evaluated to find the association between differentiation and metastasis. Lymph node metastasis was not related to the degree of differentiation. Distant metastasis was significantly related to the degree of differentiation (Fisher's exact test: p = 0.007). The result of the combination therapy is poor for patients with poorly differentiated or undifferentiated carcinoma because of distant metastases. Adjuvant chemotherapy may be necessary for them to prevent distant metastasis.