hree papaya ringspot virus strains (PRSV-W FL, PRSV-P HA, and PRSV-T), 15 potyvirus isolates related to PRSV, and four other cucurbit potyviruses (watermelon mosaic virus 2, WMV-2; watermelon mosaic virus from Morocco, WMV-M; zucchini yellow mosaic virus, ZYMV; and zucchini yellow fleck virus, ZYFV) were compared for seven properties. The PRSV strains and the 15 isolates were clearly differentiated from WMV-2 and ZYMV. Five criteria discriminated between isolates or PRSV strains. Among them, the serological properties of the capsid distinguish nine groups, the serological properties of the amorphous inclusion protein distinguish two groups, and the symptoms induced on a set of muskmelon lines distinguish four groups or pathotypes. These results were compared through a factorial analysis of multiple correspondences. It appeared that the extent of the variability observed among the PRSV isolates enlarges those already known for PRSV and for WMV-M. Moreover, the similarities between these two groups suggest that PRSV and WMV-M are related. Similar pathotypes have been observed also between some of isolates of PRSV and ZYFV. In spite of the limited number of PRSV isolates that have been studied, some conclusions can be drawn from an analysis of their geographical origin: the common strain of PRSV has been identified in America, in Africa, in Europe, and in Oceania. By contrast, the four isolates related to WMV-M have been collected only in Africa or in its vicinity. PRSV-T, collected in the West Indies, has some similarities with an isolate collected in West Africa.