Chronic rhinosinusitis with nasal polyps is strongly associated with other diseases, including asthma and allergy. The following study tested the association of the -765 G/C polymorphism of cyclooxygenase-2 (COX-2) encoding gene and the -14C/G polymorphism of protooncogen MET (MET) encoding gene with a risk of chronic rhinosinusitis with nasal polyps in a Polish population. One hundred ninety-five patients of chronic rhinosinusitis with nasal polyps as well as 200 sex-, age-, and ethnicity-matched control subjects without chronic sinusitis and nasal polyps were enrolled in this study. Among the group of patients, 63 subjects were diagnosed with allergy and 65 subjects with asthma, respectively. DNA was isolated from peripheral blood lymphocytes of patients as well as controls, and gene polymorphisms were analyzed by restriction fragment length polymorphism-polymerase chain reaction (RFLP-PCR). Ten percent of the samples have been confirmed by a second method single-strand conformation polymorphism (SSCP)-PCR. We reported that the -765 G/C COX-2 (odds ratio [OR] 7.79; 95% confidence interval [CI] 4.88-12.4, p<0.001) and the -14C/G MET (OR 2.83; 95% CI 1.74-4.61, p<0.001) were associated with an increased risk of chronic rhinosinusitis with nasal polyps among analyzed group of patients. Moreover, the group of patients without allergy or asthma indicated the association of the -765 C/G (OR 7.25; 95% CI 4.38-12.1, p<0.001 and OR 7.61; 95% CI 4.47-12.6, p<0.001) genotype of the COX-2 as wells as the -14C/G (OR 2.47; 95% CI 1.46-4.17, p<0.001 and OR 2.59; 95% CI 1.54-4.37, p<0.001) genotype of MET with an increased risk of chronic rhinosinusitis with nasal polyps. Finally, it was also found that the selected group of patients with allergy or asthma indicated a very strong association of the -765 G/C (OR 5.64; 95% CI 2.91-10.9 and OR 4.74; 95% CI 2.49-9.03, p<0.001, respectively) genotype of the COX-2 with an increased risk of chronic rhinosinusitis with nasal polyps. Thus, our results suggest that COX-2 and MET gene polymorphisms may have deep impact on the risk of rhinosinusitis nasal polyp formation, which may also depend on asthma or allergy. Our results showed that the -765 G/C polymorphism of COX-2 gene and the -14C/G polymorphism of the MET gene may be associated with the risk of chronic rhinosinusitis with nasal polyps in a Polish population.