Bone morphogenetic protein 4 (BMP4) gene is primarily involved in regulation of bone development and is considered as positive regulator for osteogenesis. The objectives of the study were to explore the polymorphism of BMP4 gene and to determine the expression profile of the predominant genotype observed in broiler (81%) and layer (95%). PCR-SSCP revealed differential pattern with AA genotype being most frequent over AB and AC genotypes. The fast-growing birds displayed higher magnitudes of growth traits over their counter layers. The mRNA expression level was relatively higher in broiler at day 42 and in layer on day 1 and lower on day 28 of both the lines. Significant difference (p≤0.05) in gene expression was observed during different stages of growth in layer line only. It can be concluded that the BMP4 gene was polymorphic and the mRNA expression varied distinctly over different developmental stages of juvenile period in broiler and layer chicken.