The traditional rice-fish farming system was selected as a "globally important agricultural heritage system" (GIAHS) by the Food and Agriculture Organization (FAO).In Zhejiang Province of China, where the pilot site for this GIAHS farming system is located, we compared the use of traditional rice varieties in rice-fish co-culture and rice monoculture, and we determined how traditional rice varieties were performed in this rice-fish system.Only 19% of the farmers who practiced rice monoculture planted traditional varieties while 52% of farmers who practiced rice-fish co-culture planted traditional varieties.