Type I collagen is composed of two alpha 1(I) chains and one alpha 2(I) chain that together form a unique triple helical structure. The genes for these chains are located on different chromosomes but their expression is tightly regulated. In order to investigate the mechanism of regulation of coordinate expression of these genes. I examined conditions for the efficient transfection of normal human skin fibroblasts with luciferase reporter gene constructs containing noncoding region of the first exon and the upper 500 base pairs sequence of the alpha 1(I) or alpha 2(I) gene. Expression ratio of these two reporter gene constructs was two to one, indicating these regions of alpha 1(I) and alpha 2(I) genes contain essential regulatory elements for the coordinate expression of alpha 1(I) and alpha 2(I) genes located on different chromosomes.