We compared outcomes of patients with severe aplastic anemia (SAA) who received granulocyte-colony stimulating factor (G-CSF)-stimulated bone marrow (G-BM) (n = 78), unstimulated bone marrow (BM) (n = 547), or peripheral blood progenitor cells (PBPC) (n = 134) from an HLA-matched sibling. Transplantations occurred in 1997 to 2003. Rates of neutrophil and platelet recovery were not different among the 3 treatment groups. Grade 2-4 acute graft-versus-host disease (aGVHD) (relative risk [RR] = 0.82, P = .539), grade 3-4 aGVHD (RR = 0.74, P = .535), and chronic GVHD (cGVHD) (RR = 1.56, P = .229) were similar after G-BM and BM transplants. Grade 2-4 aGVHD (RR = 2.37, P = .012) but not grade 3-4 aGVHD (RR = 1.66, P = .323) and cGVHD (RR = 5.09, P < .001) were higher after PBPC transplants compared to G-BM. Grade 2-4 (RR = 2.90, P < .001), grade 3-4 (RR = 2.24, P = .009) aGVHD and cGVHD (RR = 3.26, P < .001) were higher after PBPC transplants compared to BM. Mortality risks were lower after transplantation of BM compared to G-BM (RR = 0.63, P = .05). These data suggest no advantage to using G-BM and the observed higher rates of aGVHD and cGVHD in PBPC recipients warrants cautious use of this graft source for SAA. Taken together, BM is the preferred graft for HLA-matched sibling transplants for SAA. © 2011 American Society for Blood and Marrow Transplantation.