A simple purification procedure of bioactive human granulocyte macrophage colony stimulating factor (hGM-CSF) secreted in rice cell suspension culture has previously been described. In this study the protein was purified to apparent homogeneity with an overall yield of $80.1\%$ by ammonium sulfate precipitation and a single chromatographic step involving FPLCanion exchange chromatography. The purified hGM-CSF revealed at least five glycosylated forms ranging from $21.5{~}29$ kDa, and its biological activity was independent of the glycosylation pattern. This is the first purification report of recombinant hGM-CSF to apparent homogeneity from rice cell suspension cultures.