"Objectives:" To provide high quality gene expression profiles of cultured human periodontal ligament (PDL) cells, derived from deciduous teeth under tensile force. To the best of our knowledge no similar mechanical studies have been done on PDL cells derived from deciduous teeth. Elucidating such biological response might be helpful in understanding the common adverse effect of root resorption of deciduous teeth following application of orthodontic force. "Methods:" Human PDL cells were explanted from deciduous teeth roots, which had no successors and were extracted for orthodontic reasons. Once cell cultures were confluent, they were transferred to plates and subjected to either tensile force for 20 minutes or no force, which served as controls. Following the tensile force application RNA was extracted from the cells. Expression profiling performed with hybridization with DNA Microarray (Affymetrix, CA, USA) containing 8700 genes. The data was analyzed using Affymetrix software and only genes which differed from the control in a significant level of less than p<0.01 were chosen. "Results:" 461 genes were up-regulated and 271 genes were down-regulated following application of tensile force. The main functional group of genes, which was activated, was the signal transduction group. Other groups of genes, which were activated, were: cell proliferation, response to external stimuli, cell to cell signaling, cell adhesion and cell death. The main signal transduction pathway, which was activated, was the Phosphatidyl-Inositol pathway. Other pathways, which were activated, were MAPK and Integrin mediated pathways. "Conclusions:" This is the first report of PDL fibroblasts gene profile from deciduous teeth in response to mechanical tensile type of force. Obviously, further characterization of these genes followed by Proteomics analysis is essential to gain better insight of primary teeth response to orthodontic force.