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Genetic studies in mice have demonstrated a complementary role for the melanocortin-3 receptor (MC3R) and MC4R in the control of energy balance. Knockout of the MC3R in mice revealed an exclusively metabolic syndrome and increased fat mass. In the present study, we found a total of 5 novel single nucleotide polymorphisms (SNPs) of the MC3R gene in the chickens of high weight (HW) and low weight (LW) lines from divergently selected for high or low body weight at 8 weeks of age in White Plymouth Rock. Only one of the 5 SNPs led to amino acid substitution (Leu-->Arg) in HW and LW lines animals: a T/G substitution at nucleotide (nt) position 452 of coding sequence. Three of the 5 SNPs distinguished the birds from HW and LW lines: an A/G substitution at nt position 549 in LW line, an A/G substitution at nt position 882 in HW line, and a C/T substitution at nt position 894 in LW line, respectively. Another SNP was presented only in one of two HW line animals: a C/T substitution at nt position 564. Of the 5 SNPs, only A/G polymorphism at nt position 549 is located within a Dde I restriction enzyme recognition site. We designed a PCR-RFLP test based on the enzyme Dde I and screened the chickens for HW and LW lines' intercross. Analysis of variance revealed a significant influence of the MC3R genotype on body weight in the chickens for both sex and abdominal fat mass in male chickens. The result suggests that the MC3R as a candidate gene can explain significant difference for body weight in the intercross chickens.