Background Subungual melanoma (SM) is rare. The lesions are thick at the time of diagnosis. Few studies have evaluated SM in Brazil. Objective The objective of this study was to investigate the factors associated with the survival of SM patients from the Brazilian National Cancer Institute. Methods One‐hundred and fifty‐seven patients diagnosed with SM were included in this study. We evaluated the epidemiologic, clinical, and histopathological data. Overall survival (OS) and relapse‐free survival (RFS) curves were computed using the Kaplan‐Meier method. Multivariable analyses were conducted using the Cox proportional hazard regression model. Results Among the 157 patients, 87 (55.4%) were female. The median age was 68 years old. Median tumor depth was 6.0 mm. Lesions were ulcerated in 94 (59.9%). OS and RFS rates for 5 years were 61.0% and 41.8%, respectively. Median follow‐up time was 28 months. The factors associated with OS were Breslow thickness and ulceration, and for RFS, they were the anatomical site, Breslow thickness, and ulceration. Conclusion This is the largest series of SM patients. The 5‐year OS and RFS rates were low (61.0% and 48.2%, respectively), and the main prognostic factors for OS were Breslow thickness and ulceration.