The human parvovirus, adeno-associated virus-2 (AAV-2), has many attributes that recommend its use as a gene transfer vehicle, including a broad tissue tropism, the ability to integrate stably into the host genome, and efficient transduction of cells which proliferate slowly. However, application to human gene therapy is currently limited by existing methods for generation of recombinant AAV (rAAV), resulting in relatively low transducing titres. In an attempt to overcome some of these problems, we have developed a defective adenoviral vector which improves the efficiency of rAAV vector delivery to cells in which rAAV is propagated, and from which the rAAV genome can be efficiently rescued. A functional copy of the p47phox gene was successfully transferred to cell lines derived from patients with autosomal recessive chronic granulomatous disease (CGD) by rAAV recovered in this way, and function of the NADPH-oxidase was restored to levels which were stable for at least 8 weeks. This method for generation of rAAV, although still limited by the need for cotransfection of AAV Rep and Cap functions, may permit recovery of higher titre transducing stocks from cell lines in which these genes are stably incorporated, and significantly reduces the risk of contamination with wild-type adenovirus (wtAd).