We retrospectively studied 329 patients with squamous cell carcinoma (SCC) of the tongue who were treated at The Chinese Academy of Medical Sciences, Peking Union Medical College, Department of Head and Neck Surgery of Cancer Hospital during the past 25 years (1975–2000). The patients were followed up for more than 36 months, and 28 (9%) developed 29 second primary carcinomas. The characteristics of the index tumour including the clinical appearance (10% nodular, 8% ulcerated), the site (10% anterior, 9% posterior, and 6% lateral), the classification (13% T1, 9% T2), the stage (12% stage I, 11% stage II, and 7% stage III), the histological appearance (7% well-differentiated, 14% moderately differentiated, 36% poorly differentiated, and 2% unknown), and the type of treatment given (18% resection only, 4% radiation only, and 6% combined treatment) were recorded. Twenty-three of the 29 second primary lesions developed in the upper aerodigestive tract with the oesophagus the most common site (79%). During the follow-up period, 14 patients died from causes associated with the second primary lesion and 5 from unrelated causes, and 9 patients were still alive at the time of follow-up. The prognosis for patients who develop second primary lesions is poor.