Acute GVHD (aGVHD) is a major cause of morbidity and mortality after unrelated BMT (UBMT). Our purpose was to analyze the role of extracorporeal photochemotherapy (ECP) in controlling grade II-IV aGVHD in children given UBMT. Of 41 consecutive children, 31 developed grade II-IV aGVHD after UBMT: 16 had a good response to steroids (GR group), whereas 15 underwent ECP (ECP group) within 100 days of UBMT. Eligibility criteria for starting ECP were steroid resistance, dependence or viral reactivations. Criteria for judging response to aGVHD treatment were that the resolution of all signs were considered a complete response (CR), at least a 50% improvement was classified as a partial response (PR) and stable or progressive disease was judged as no response (NR). On completing ECP, the CR rate was 73%, whereas the GR group had a CR rate of 56% by day 100. The 2-year overall survival and progression-free survival rates were 57 and 67% in the GR group vs 85 and 87% in the ECP group. Our data seem to suggest that ECP may improve outcome in patients after UBMT. These findings need to be confirmed in a larger population.