Activation of the nuclear hormone receptor perioxisome proliferator-activated receptor gamma (PPARgamma) inhibits cell growth and induces apoptosis in several human cancers. We have hypothesized that PPARgamma mRNA levels could be predictors of the differentiation and survival of lung cancer. The study included 77 lung cancer cases. The mRNA levels were quantified by real time reverse transcription-polymerase chain reaction (RT-PCR) using LightCycler. The PPARgamma mRNA levels were decreased in tumor tissues from lung cancer (0.579 +/- 1.255) compared to the normal adjacent lung tissues (4.191 +/- 2.868) (P = 0.0001). No significant difference in PPARgamma mRNA levels was found among gender, age, and pathological subtype. The PPARgamma mRNA levels were higher in tumor tissues from higher differentiated lung cancer. The NSCLC patients with low PPARgamma mRNA expression (< 0.5) had significantly worse survival than the patients without low PPARgamma mRNA levels (P = 0.0438, Breslow-Gehan-Wilcoxon test; P = 0.0168, Cox's proportional-Hazards regression model). Thus, PPARgamma mRNA levels may serve as a prognostic marker in lung cancer. Using the LightCycler RT-PCR assay, the determination of PPARgamma mRNA levels might provide a potential marker for treatment of lung cancer by PPARgamma agonist. However, further studies and a longer follow up are needed to confirm the impact of PPARgamma in the biological behavior of the tumor.