Abstract: Humans constantly lose epithelial cells, and these biological traces are frequently studied in the context of criminal investigations. The objective of this work was to examine the genetic profile in samples of forensic interest (nail and skin epithelial cells) of bone marrow transplant patients and discuss its forensic and clinical implications. The genetic profile of nail, epidermal cells and blood samples of patients receiving HSCT was analyzed by the amplification and sequencing of 38 insertion/deletion polymorphisms and 15 short tandem repeat polymorphisms. In this analysis, the age of patients and donors, the time elapsed from the transplant, the type of conditioning prior to the transplant and whether the patient suffered graft-versus-host disease were considered. Donor chimerism can be detected in the DNA extracted from nail and skin epithelial cells of transplant patients. No statistically significant correlation was found between the type of conditioning and the percentage of donor DNA in nail (p?>?0.05). A positive correlation, without statistical significance, was encountered when we analyzed the relationship between the time elapsed from the transplant with the percent donor chimerism found in epithelial cells of the epidermis and in nails. We conclude that within a judicial context (e.g. when testifying as an expert witness) it is necessary to consider whether we are facing a possible transplant patient or a person who has been a bone marrow donor.