The purpose of this study was to evaluate the cytotoxicity of acrylic and methacrylic acid (AA and MA), propanoic acid and isobutylic acid (PRA and IBA) which were the corresponding saturated carboxylic acids, 2-hydroxylethyl methacrylate and acrylate (HEMA and HEA), and hydroquinone (HQ). The growth of the fibroblast when exposed to AA decreased with increase of the acid, and was less than when exposed to MA. The growth when exposed to their corresponding saturated acids, PRA and IBA, showed a similar tendency to AA and MA. The growth of fibroblasts exposed to 5 mmol/L HEMA after 4 days and 3 mmol/L HEMA after 6 days was significantly different compared with that without HEMA. The growth in 1, 3, and 5 mmol/L of HEA after 2 days was markedly decreased compared with that without HEA, and the cells were probably lifeless. The growth when exposed to HQ was extremely lower than their acids.