The immune system appears to play a role in the development of squamous intraepithelial lesions (SIL) and their progression to cancer. We have developed a technique to isolate and cultivate lymphocytes either from the epithelium or from the underlying stroma of small biopsies from the normal exocervix, the transformation zone (TZ) and SIL. The majority of cells derived from the epithelium of all biopsies were CD8+ T cells. No major difference was observed for the lymphocyte phenotype. Among all cytokines tested by ELISA (IL10, IL4 and IFNγ), only IL10 was significantly higher in the TZ in comparison with the exocervix. In cultures derived from the stroma, a decreased percentage in T cells was observed in the TZ and SIL in comparison with the exocervix. This decrease in T cells concerned CD8+ (SIL) and TCRγδ+ T cells (TZ and SIL). We did not observe any difference in IL10 or IL4 production, although patients with SIL produced more IFNγ. The higher levels of IL10 production by lymphocytes derived from the epithelium of the TZ might contribute to the predisposition of this region to cervical carcinogenesis.