BACKGROUND Gene transfer is a new territory for clinicians. Intractable disorders might be approached in such a way. Adeno-associated virus (AAV) vector has been transfected successfully into a variety of tissues including skin. We evaluated the ability of this vector to transfer and cause expression of the reporter gene in human keloid tissue. METHODS Human keloid specimens were injected with an AAV vector encoding beta-galactosidase and incubated for 4 weeks after injection. The presence of mRNA and beta-galactosidase enzymatic activity were assayed by reverse-transcriptase polymerase chain reaction and the X-gal technique. RESULTS Gene expression shown by reverse-transcriptase polymerase chain reaction was observed in keloid tissue 4 weeks after injection, and so was the positive X-gal staining. CONCLUSION Our results showed that AAV vector could transduce human keloid tissue effectively. Replacement of the reporter gene with a functioning gene might be feasible for keloid treatment.