Objective To transfect the p53 and p21 gene into the leiomyoma cells isolated from patients and observe their influence on the cell proliferation, leukemia inhibitory factor production, and gene expression of collagen type I as well as tumor necrosis factor-α (TNF-α) of cultured cells. Design Prospective study. Setting An assisted reproductive technology (ART) and genetic unit of a medical center. Patient(s) Leiomyoma cells isolated from leiomyoma tissue of 12 patients were divided into three groups:  vehicle DNA,  p53 gene, and  p21 gene transfections. Intervention(s) The pcDNA3.1 was used as vector to carry p53 and p21 genes for transfer. After gene transfection, RNAs of the leiomyoma cells were extracted for further analyses of gene expression. Main outcome measure(s) Relative cell numbers were determined by 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) assay. The leukemia inhibitory factor (LIF) concentration was determined with ELISA. Gene expressions of collagen type I and TNF-α were detected by reverse transcriptase-polymerase chain reaction (RT-PCR). Gene expression of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) was used as an internal control. The cell proliferation, LIF production, as well as gene expressions of collagen type I and TNF-α in each group were compared. Results Relative cell numbers (%)/LIF production (in picograms per milliliter) in each group were:  100/58,  71/43, and  106/65. The ratios of gene expression of collagen type I/TNF-α with GAPDH in each group were:  1.64/0.335,  1.25/0.434, and  1.77/0.234. Conclusion(s) Transfection with p53 significantly inhibits proliferation of leiomyoma cells and decreases collagen type I gene expression and LIF production. The p21 transfection inhibits TNF-α gene expression.