This study aimed to investigate the association between charcoal-burning suicide attempts and the risk of developing dementia. A nationwide, matched cohort, population-based study enrolled a total of 4103 patients with newly diagnosed charcoal-burning suicide attempts, between 2000 and 2010, which were selected from the National Health Insurance Research Database of Taiwan, along with 12,309 controls matched for sex and age. After adjusting for confounding factors, Fine and Gray’s competing risk analysis was used to compare the risk of developing dementia during the 10-year follow-up period. Of the enrolled patients (n=16,412), dementia developed in 303 (1.85%), including 2.56% in the study group (105 in 4103) and 1.61% (198 in 12,309) in the control group. The Fine and Gray’s survival analysis revealed that the patients with charcoal-burning suicide attempts were likely to develop dementia, with a crude HR of 5.170 (95% CI 4.022 to 6.644, p<0.001). After adjusting for age, sex, comorbidity, geographic area and urbanization level of residence, and monthly insured premium, the adjusted HR was 4.220 (95% CI 3.188 to 5.586, p<0.001). Suicide attempts were associated with an increased risk of degenerative dementia in this study. Patients with charcoal-burning suicide attempts had a fourfold risk of dementia than the control group.