A chromoprotein from Pleurotus salmoneostramineus L. Vass. has been purified and crystallized. The needle-shaped crystal has monoclinic space group C2 with the cell dimensions of a = 118.5, b= 59.7,0 c = 31.8 A and beta = 114 degrees. The crystal diffracts to 1.8 A resolution with a synchrotron radiation X-ray source.