Late complications of allogeneic hematopoietic stem cell transplantation (HSCT) include a risk of secondary malignancies. Optimization for early diagnosis and treatment of oral premalignant or malignant lesions requires an assessment of potential predisposing risk factors. The medical records of patients who developed oral epithelial dysplasia (OED) and oral squamous cell carcinoma (OSCC) following allogeneic-HSCT were reviewed. Data on HSCT course, chronic graft-versus-host disease (cGVHD), and clinical outcome were recorded; landmark survival was calculated. Twenty-six patients with OED (n=8) and OSCC (n=18) were identified with a median follow-up of 26.5 and 21.5 months, respectively. Premalignant and malignant oral lesions were diagnosed at a median time of 2.5 and 8 years after HSCT, respectively. Chronic GVHD was present in 96% of patients and of these, 96% had oral involvement. Multifocal oral cancer was found in 28% of cases, and localized recurrence was observed in 44% of cases. These results suggest that oral cGVHD may be considered a potential risk factor for the development of OSCC following allogeneic-HSCT. The observation that oral cancers were frequently multifocal and recurred locally suggests that these cancers may be more aggressive. Vigilant follow-up and coordination of care are critical.