This study evaluated ALDH1A1, an ALDH1 subtype implicated in head and neck cancer stem cells, and examined its association with histopathological features (depth of invasion, worst pattern of invasion, perineural invasion, grade, inflammation, TNM stage) and prognostic outcomes in tongue tumors.<h4>Materials and methods</h4>This cohort study included 55 confirmed cases of tongue squamous cell carcinoma retrieved from the pathology archives of the Cancer Institute, Imam Khomeini Hospital Complex, Tehran, Iran. The gene discussed is ALDH1A1; the disease is tongue squamous cell carcinoma.