Gene therapy has become a field of intense research. Transferring of genetic material allows different therapeutic approaches and requires its introduction into viral and non viral vectors such as liposomes. Physiological events after vector administration, however, interfere on the final rates of gene expression. Since genetic material is disposed as the actual therapeutic agent, comprehension of pharmacological parameters  is necessary. Different protocols can be used for studying the efficacy of gene transfer and expression. Fluorescence spectrophotometry allows analysis of entire tissues, including all cell types and wave lengths. Objectives: This study aimed detecting green fluorescent protein (GFP) by fluorescence spectrofotometry after transfection of HepG2 cells using liposomes. Methods: Cellular basal fluorescence was determined for concentrations of 10 to 10⁷ cells per mL. Cells were transfected with pTracer plasmid containing GFP gene (naked or associated to Lipofectamine) and pREP9 plasmid (fluorescence negative control). Transfected and non transfected control cells were submitted to fluorescence spectrophotometric analysis at times 0, 12, 24 and 48 h after transfection and to fluorescene microscopy. Results: Cellular basal fluorescence was linear up to 10⁵ cells per mL. Cells treated with pTracer/Lipofectamine showed, in general, higher fluorescence than those treated with naked pTracer when submitted to fluorescence spectrophotometry. Fluorescence microscopy confirmed such results.  Conclusions: It was possible to differentiate transfected and non-transfected cells, as well as to compare levels of fluorescence according to time. This method has the advantage to be uniform for different cell types, which allows the analysis of whole tissues, and may be a useful tool for screening the efficacy of transfection systems.