Human pulp tissue was obtained from the first lower right molar of a 24 year old male patient during oral surgery. The tooth was healthy with no evidence of carious lesions. 6 cultures were initiated by the explant method. The cells were isolated and carried through 8 passages. Samples from different passages were fixed, dehydrated, and prepared for scanning electron microscopic observations. Some cells had a smooth surface, while others showed microvillous projections from their surface. Both cell types were seen in the same culture. However, in the third passage all the cells were of the smooth surface type. The cells were interconnected by a system of fibrils that were related to their surface. These fibrils also appeared to anchor the cells to the surface of the coverslips on which they were growing. This study showed that more than one cell type apparently existed in human pulp fibroblasts culture. Whether these cell types have different functional properties, or whether they are different developmental stages of the same cell type in culture, remain to be determined.