Objective: Nonmyeloablative stem cell transplantation (NST) is a relatively new type of hematopoietic stem cell transplantation (HSCT) that has gained wider use in the last decade. Oral effects of NST have not been described. The goal of the study was to evaluate the oral mucosal effects, including oral acute graft versus host disease (aGVHD), in patients undergoing NST in comparison to patients undergoing myeloablative HSCT. Method and Materials: This prospective, longitudinal pilot study included 34 consecutive patients undergoing HSCT. Demographic data were collected. Patients were evaluated every 2 weeks between baseline and day 100 posttransplantation. Statistical methods included univariate and multivariable regression analyses (level of significance, P .05). Results: Patients undergoing NST had significantly less oral aGVHD (P = .032, OR = 0.11, CI: 0.02-0.83). Systemic aGVHD-related lesions were common in all patients. The prevalence of opportunistic oral infections was not statistically different between the NST and ablative groups (P = .94). Conclusions: In this pilot study, cancer patients treated with NST had a lower incidence of oral aGVHD than those receiving myeloablative HSCT. The incidence of other oral soft tissue lesions, including opportunistic infections, was not affected by the type of HSCT. Keywords: GVHD, hematopoietic stem cell transplantation, infection, myeloablative, oral