119 patients scheduled for instrumented single-level posterolateral lumbar fusion were randomized to a graft source of either osteogenic protein-1 (OP-1; Stryker) or autologous iliac crest bone (ICBG). The purpose of this study was to evaluate if OP-1 was non-inferior to ICBG based on an overall success endpoint which was defined as successful fusion, a relative improvement on the Oswestry Disability Index (ODI) of 20% from baseline, no deterioration in neurological status, and no requirement of secondary surgery. The results of this study failed to demonstrate the non-inferiority of OP-1 in comparison to ICBG for overall success, predominantly due to a significantly lower rate of fusion success.