The potential of cytokine gene therapy using naked plasmid DNA encoding human IL-2 cDNA in a xenograft nude mouse model was investigated. To overcome the T cell deficiency in nude mice, Adoptive T Cell Transfer [ATCT] into tumour bearing nude mice was performed. The migration of T cells was tracked in vivo using CFSE labeling. IL-2 in circulation was observed till day 15 with the levels reaching a peak by day 3. Significant activation of transferred T cells (CD69+, CD25+) as well as significant increase in levels of NK cells (CD49b+) was seen in animals receiving IL-2. Tumour regression was observed in the IL-2+ ATCT group.