Vascular endothelial growth factor (VEGF) is a major mediator of angiogenesis and lung cancer progression. We hypothesized that VEGF polymorphisms may modulate the risk of radiation pneumonitis (RP) in non-small cell lung cancer (NSCLC) patients treated with definitive radiotherapy. We genotyped three potentially functional VEGF single nucleotide polymorphisms (&460 T similar to>similar to C [rs833061], &634 G similar to>similar to C [rs2010963] and +936 C similar to>similar to T [rs3025039]) and estimated the associations of their genotypes and haplotypes with severe radiation pneumonitis (RP =grade similar to 3) in 195 NSCLC patients. We found that the VEGF genotypes of rs2010963 and rs3025039 single nucleotide polymorphisms as well as the &460C/&634G/+936C haplotype were predictors of RP development (adjusted hazard ratio [adjHR]similar to=similar to 2.33, 95% confidence interval [CI], 1.015.37, P similar to=similar to 0.047 for CC vs GG genotypes; adjHR similar to=similar to 28.13, 95% CI, 5.24151.02, P similar to<similar to 0.001 for TT vs CC genotypes; and adjHR similar to=similar to 2.51, 95% CI, 1.274.98, P similar to=similar to 0.008 for T-C-T vs C-G-C haplotypes). In addition, there was a trend towards reduced RP risk in patients carrying an increased number of protective VEGF genotypes. Our data suggest that VEGF polymorphisms can modulate the risk of radiation pneumonitis in NSCLC patients treated with definitive radiotherapy. Large and independent studies are needed to confirm our findings. (Cancer Sci 2012; 103: 945950)