Hematopoietic stem cells (HSCs) have unique properties of self-renewal, differentiation and proliferation. HSCs are easily accessible, and can be readily delivered back to patients by autologous transplantation, which renders them as attractive targets for ex vivo gene therapy. The adeno-associated virus (AAV) vectors have to date not been associated with any malignant disease, and have gained attention as a potentially safer alternative to the more commonly used retroviral vectors for HSC gene therapy. Although conflicting data exist with regard to HSC transduction by AAV vectors, in this review, we provide an overview of AAV-mediated HSC gene transfer - obstacles as well strategies to improve the transduction efficiency - and the potential use of AAV vectors for gene therapy of human diseases involving HSCs.