A recombinant strain of Bacillus subtilis engineered for endocellular expression of human interleukin-l receptor antagonist (IL-1ra) was subjected to sporulation. The recombinant protein was recovered from the sporulation supernatant in quantities, purity, and activity comparable with those obtained from a traditional cell lysate. Thus, exploitation of this natural mechanism of autolysis could overcome problems of intact protein recovery related to the cell disruption step.