Intronic rs12505266 of CLOCK was significantly associated with an increased predisposition to breast cancer among recessive homozygous genotypes OR = 1.22 (0.83–1.79), p = 0.057 and at marginal significance under a recessive genetic model OR = 1.38 (0.97–1.96), p = 0.07. Here, CLOCK is linked to breast carcinoma.