Physical therapists (PTs) frequently provide neuromusculoskeletal treatment for patients who incidentally may have one or more tattoos. Low level light therapy (LLLT) is one of the modalities commonly used by physical therapists to decrease pain and facilitate healing.This case report describes a 22 year old man who was given LLLT to address his complaints of musculoskeletal pain.Blistering of the skin was documented over the LLLT application site, a black tattoo.The blisters, which formed after the LLLT treatment were most likely caused by the inadvertent and unexpected heating of the iron oxides and/or the metal salts in the tattoo's black pigment. PTs should exercise caution when applying LLLT in the presence of dark tattoos.