P. chrysogenum rhamnogalacturonan (RG) rhamnohydrolase (PcRGRH78A) was purified. A gene encoding PcRGRH78A was cloned and overexpressed. Specificity of PcRGRH78A was different from that of an α-rhamnosidase. PcRGRH78A was specific for terminal rhamnose without galactose residues in RG. The present study is the first report of a gene encoding RG rhamnohydrolase.