Total proteins (both native and denatured) and three isoenzyme systems (esterases, malate dehydrogenases, superoxide dismutases) were analysed for eightPhytophthoraspecies and for eight strains ofP. nicotianae.The results obtained showed low intraspecific variability (62‐100% of similarity index) forP. nicotianaeand allowed the characterization ofP. capsici, cinnamomi, cryptogea, megakarya, megasperma, nicotianae, palmivoraandcitrophthoraby the polyacrylamide gel electrophoretic profiles of native proteins and isoenzymes. The interspecific variability between these eight species is high (27‐49% of similarity index). The results obtained support the use of these macromolecular criteria as an aid to the identification ofPhytophthora