In order to probe into the mechanism of glycidyl methacrylate (GMA)-induced cell transformation, the effects of GMA on gap junctional intercellular communication (GJIC) in human lung, embryonic fibroblasts(HLEF) were studied by using scrape-loading and dye transfer(SLDT) technique. HLEF cells were treated with GMA at concentrations of 0.5, 2.5 and 5.0 mg/L for 12 hours and Lucifer Yellow was introduced by scrape-loading after exposure. The GJIC in exposed cells and that of control were determined directly as the diffusion extent of fluorescent dye into adjacent cells. The results indicated that GMA could inhibit the GJIC in exposed cells in a dose-dependent manner. Significantly decreased GJIC was found in 2.5 and 5.0 mg/L dose groups. It was suggested that the inhibition of GJIC might be one of the mechanisms responsible for GMA-induced cell transformation.