Only 30% of children have a matched family donor (MFD). Alternative donors can be found from volunteer unrelated donor (UD) panels, and almost every child has a haploidentical parental donor (Haplo). The outcome of alternative donor BMT has previously been inferior due to increased graft rejection and GVHD. The recent outcome of 121 consecutive children undergoing MFD, UD, and Haplo BMT between 1994 and 1997 was analysed. [table in text] Preparative regimens for MFD/UD/Haplo BMT respectively included TBI in 30%/36%/11%, chemotherapy only in 59%/64%/89%, Campath 1G or none n 14%/ 0%/0%. The balance of GVHD and rejection was addressed by T-cell depletion (Campath 1M) in 2/71 MFD BMTs, T-cell depletion with addback of 5 x 10(4) T cells/kg on day zero in 33/41 UD BMTs, and T cell depletion of purified mobilised peripheral blood CD34+ cells and bone marrow in 9/9 Haplo BMTs. Stable engraftment was achieved in 68/71, and 35/41 (one patient after 2nd BMT) and 7/9 MFD, UD, and Haplo BMTs respectively. Median follow up, survival, disease free survival and, death rates for MFD/UD/Haplo BMT were 12/12/12 months, 74%/77%/78%, 69%/67%/67%, and 27%/23%/23% respectively. Within a wide range of paediatric diseases the outcome of alternative donor BMT now parallels that of MFD BMT.