To obtain a better understanding of the molecular variation of sweet potato viruses in China, 131 samples were collected from symptomatic sweet potato plants and used for RT-PCR analysis of the heat shock protein 70 (hsp70) gene sequence of sweet potato chlorotic stunt virus (SPCSV) and the coat protein (CP) gene sequences of five potyviruses (SPFMV, SPVC, SPVG, SPLV and SPV2). The hsp70 sequences that were obtained provided evidence for the presence of two distinct strains of SPCSV. Analysis of the CP sequences amplified from the samples indicated that all five potyviruses infect sweet potato in China, and three different strains of SPFMV and two of SPVG were found.