Previous studies have suggested an association of personal hair dye use with bladder and hematopoietic cancers. Risks for brain tumors are not well understood. The authors investigated associations between use of synthetic hair dyes and risk of brain tumors in a hospital-based case-control study. The study included adults newly diagnosed with glioma (n = 489), meningioma (n = 197), or acoustic neuroma (n = 96) between 1994 and 1998 at three urban US hospitals and 799 controls. Odds ratios were estimated and 95% confidence intervals were calculated using unconditional logistic regression. Detailed exposure histories were obtained by interview. There was no consistent pattern of elevated odds ratios for glioma, meningioma, or acoustic neuroma with use or prolonged use of permanent, semipermanent, temporary, or gradual hair dyes. Although use of permanent brown hair dye for 20 or more years was associated with glioma among women, the estimate was imprecise (odds ratio = 3.8, 95% confidence interval: 1.2, 12.5) and was based on just 13 exposed cases; thus, this could be a chance finding. Overall, there was little consistent evidence for an association of synthetic hair dye use with glioma, meningioma, or acoustic neuroma. However, prolonged use of dark-colored permanent dyes warrants further investigation given the high prevalence of hair dyeing.