Aims Chronic inflammation is linked to cancer. This study aims to evaluate the association between chronic rhinosinusitis (CRS) and nasopharyngeal carcinoma (NPC) through a Taiwanese nationwide database. Methods We used the National Health Insurance Research Database between January 1, 2003, and December 31, 2012. The starting date is either the date of the first clinical visit or the diagnosis of CRS. Patients were followed up until the first occurrence of target disease or the last date of medical record. Propensity score 1 to 2 matching was used to match pairs of patients with/without CRS. Results A total of 951 380 eligible patients were included in our study, with 36 210 patients diagnosed with CRS. After 1 to 2 propensity score matching, non‐CRS cohort consisted of 69 258 patients and CRS cohort consisted of 34 629 patients. CRS was associated with the risk of developing NPC (adjusted OR = 2.23; 95% CI, 1.61–3.09). However, no significant association among CRS and NPC was observed in patients followed up for more than 1 year (adjusted OR = 1.16; 95% CI, 0.76–1.78). Conclusions Patients with CRS diagnosis have relationship with developing NPC within 1 year of follow‐up, but not for longer intervals. The short‐term association may be due to reversed causation or biased diagnosis. Accordingly, the study suggests CRS a weak role for NPC. Patients with chronic rhinosinusitis have relationship with developing nasopharyngeal carcinoma within 1 year of follow‐up, but not for longer intervals. The short‐term association may be due to reversed causation or biased diagnosis.