Since variation in specific genes affects the levels of IGF1 and IGFBP3 and may influence mammographic density as well as breast cancer susceptibility, we set out to analyze 24 SNPs in IGF1, IGF1R, IGF2, IGF2R, IGFBP3 and IGFALS and their association with mammographic density and plasma levels of IGF1 and IGFBP3 among 964 postmenopausal women. The gene discussed is IGF1; the disease is breast cancer.