Hair dyes have been evaluated as possibly being mutagenic and carcinogenic in animals. Studies of the association between human cancer risk and use of hair dyes have yielded inconsistent results. The authors evaluated the risk of lymphoid malignancies associated with personal use of hair dyes. The analysis included 2,302 incident cases of lymphoid neoplasms and 2,417 hospital- or population-based controls from the Czech Republic, France, Germany, Ireland, Italy, and Spain (1998-2003). Use of hair dyes was reported by 74% of women and 7% of men. Lymphoma risk among dye users was significantly increased by 19% in comparison with never use (odds ratio (OR) = 1.19, 95% confidence interval (CI): 1.00, 1.41) and by 26% among persons who used hair dyes 12 or more times per year (OR = 1.26, 95% CI: 1.00, 1.60; p for linear trend = 0.414). Lymphoma risk was significantly higher among persons who had started coloring their hair before 1980 (OR = 1.37, 95% CI: 1.09, 1.72) and persons who had used hair dyes only before 1980 (OR = 1.62, 95% CI: 1.10, 2.40). Personal use of hair dyes is associated with a moderate increase in lymphoma risk, particularly among women and persons who used dyes before 1980. Specific compounds associated with this risk remain to be elucidated.