AbstractMost of the evidence for the carcinogenicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in humans has centered around whether it causes malignant lymphomas (ML) and soft-tissue sarcomas (STS). A critical review of the literature indicates that the evidence does not support a causal role for TCDD in the etiology of ML. For STS, the evidence does not specifically incriminate TCDD either, although there is room for doubt. Cancers of other sites, particularly of the respiratory system and thyroid which were found to be statistically significantly in excess in either of the two largest studies of combined cohorts of occupationally exposed workers, were identified as candidate tumors for which a possible etiological role of TCDD might need investigation in future studies.