Hereditary nonpolyposis colorectal cancer (HNPCC) is primarily linked to colorectal and endometrial cancer, but is associated with a broad tumor spectrum. Though not formally part of the syndrome, occasional sarcomas have been reported in individuals with HNPCC. We used the national Danish HNPCC-register to identify HNPCC families in which sarcomas had been diagnosed. Fourteen sarcomas were identified in families with mutations in MSH2, MSH6, and MLH1. The median age at sarcoma diagnosis was 43 (15-74) years. Soft tissue sarcomas predominated followed by uterine sarcomas and eight histopathological subtypes were represented with recurrent diagnoses of liposarcoma, leiomyosarcoma, and carcinosarcoma. Tumor tissue from eight cases was available for analysis of mismatch-repair (MMR) status using immunohistochemical staining and analysis of microsatellite instability, which revealed MMR defects in six of the eight tumors investigated. This suggests that sarcomas may be part of the HNPCC tumor spectrum and that colorectal cancer should be considered in the family history of sarcoma patients.