Background National Health Insurance (NHI), launched in 1995 in Taiwan, lightens patient's financial burdens but its effect on the suicide risk in cancer patients is unclear. We aimed to investigate the impacts of the NHI on the suicide in newly diagnosed cancer patients. Methods We identified patients with newly diagnosed cancer from the nationwide Taiwan Cancer Registration from 1985 to 2007, and ascertained suicide deaths from the national database of registered deaths between 1985 and 2009. Standardized mortality ratio (SMR) of suicide risk among patients with cancer was calculated, and the suicide risk ratios were examined by gender, age group, and prognosis. Results For the 916 337 registered cancer patients with 4 300 953 person‐years, 2 543 died by suicide, with a suicide rate of 59.1 per 100 000 person‐years. Compared to the general population, cancer patients had an SMR of 2.47 for suicide, with a higher figure for males (2.73), age 45 to 64 (2.89), and cancer of poor prognosis (3.19). The suicide risk was highest in the first 2 years after the initial diagnosis. Comparing the cohorts of the period before (1985 to 1992) and after (1996 to 2007) the launch of NHI, we saw a reduction in the SMR within the first 2 years after cancer diagnosis (20%), with more prominent reduction for females (29%), age under 45 (69%), and cancer of good prognosis (33%). Conclusions A universal health coverage relieving both physical and psychological distress may account for the post‐NHI reduction of immediate suicide risk in patients of newly diagnosed cancer.