Gene therapy has become a focus not only in the study of cancer but also lifestyle-related diseases. In case of chronic rhinosinusitis with nasal polyps and aspirin-induced asthma, nasal polyps poorly respond to a local administration of steroid. The Bax and Bcl-2 proteins play important roles in the regulation of apoptosis. The treatment of steroid (prednisone) induced apoptosis in the fibroblast. The Bax accelerates apoptosis. Apoptosis is very important in the anti-inflammatory mechanism. In this study, we investigated whether the overexpression of Bax in human fibroblasts influences apoptosis by treatment with a steroid (prednisolone) in vitro. Human nasal fibroblasts were isolated from small pieces of nasal polyp and were transfected with a bax gene-bearing mammalian expression vector. Human nasal fibroblasts were transiently transfected with the expression vector hBaxpcDNA3 (Bax-NF) or native pcDNA3 (Neo-NF). Both transfectants (Bax-NF, Neo-NF) and wild-type-nasal fibroblast (wt-NF) were cultured in conditioning medium and treated with each concentration of prednisolone for 72 h. Prednisolone at a concentration of 10 ng/ml decreased the viability of Bax-NF compared to that of Bax-NF in the absence of prednisolone. The cytotoxicity of prednisolone to Bax-NF was significantly higher than that to Neo-NF or wt-NF (p < 0.01) and the susceptibility of Bax-NF to prednisolone was about 1,000 times that of Neo-NF or wt-NF. We found that the transfer of the exogenous bax gene enhanced the induction of apoptosis by steroid-treatment in human nasal fibroblasts. Therefore, we suggest that exogenous Bax protein expression by gene transfer might be useful for the treatment of nasal polyps. We will further the preclinical study in improving steroids dose and in adopting to transfer bax gene to the nasal polyps by intranasal injection, thus providing a more effective and safer way for the nasal polyps that poorly respond to a local administration of steroids.