Plant cells are increasingly used as alternative host organisms for recombinant protein production requiring post-translational modifications because they have relatively low risks of hazardous viral contamination compared to animal cells. On the other hand, the plant cell culture route has intrinsic disadvantages, including a relatively low expression titer and difficulties in the purification. We developed a simple and scalable, chromatography based process to purify rhGM-CSF from recombinant rice cell culture. It consisted of cell removal by microfiltration, ammonium sulfate precipitation, anion exchange chromatography, and SEC-HPLC. alpha-Amylase, used as a leader sequence in the expression vector, was the major impurity protein co-purified with rhGM-CSF. The purification process resulted in a final purity of ca. 95% (as verified by size exclusion chromatography) and an overall recovery yield of ca. 48% from the culture broth (as verified by ELISA).