We used a large population-based case-control study to determine whether three known p53 polymorphisms, intron 3 16 bp duplication, codon 72(Arg/Pro) and intron 6 MspI restriction fragment length polymorphism, alter the risk for breast cancer in German women. For all three polymorphisms, the odds ratios (ORs) for breast cancer were increased in women carrying the rare allele; however, this was statistically significant only for the 16 bp duplication polymorphism. Compared with the 16 bp duplication wild-type A1/A1 genotype, ORs for A1/A2 genotype and A2/A2 genotype were 1.3 [95% confidence interval (CI) 1.0-1.7] and 1.7 (95% CI 0.8-3.4), suggesting an allele dosage effect (trend test, P = 0.03). Significant evidence was found for a differential effect by family history of breast cancer (P = 0.03 for interaction), with the OR being 5.3 among women with a first degree family history. Our data suggest that inheritance of an intronic polymorphism in the p53 gene increases breast cancer risk appreciably in women by the age of 50 years with a family history of breast cancer in the German population.