We analyzed the relation between hair dye use and the risk of Hodgkin's disease (HD), non-Hodgkin's lymphoma (NHL), multiple myeloma (MM) and soft tissue sarcomas (STS) in a hospital-based case-control study conducted between 1985 and 1997 in northern Italy. Cases included 158 patients with histologically confirmed incident HD, 446 with NHL, 141 with MM, 221 with STS and controls included 1,295 patients with acute nonneoplastic conditions. Compared to never use of any type of hair dyes, the odds ratio (OR) for ever use was 0.68 (95% confidence interval, CI, 0.40-1.18) for HD, 1.03 (95% CI 0.73-1.44) for NHL, 1.17 (95% CI 0.70-1.97) for MM and 0.73 (95% CI 0.45-1.17) for STS. The OR were close to unity for permanent and semipermanent dyes analyzed separately or when the analysis was restricted to women. Our study indicates that there is no appreciable association between ever use of any type of hair dyes and the risk of HD, NHL, MM or STS.