One–dimensional slab polyacrylamide gel electrophoretic techniques, staining systems and isoenzyme banding patterns for 14 soluble enzymes separated from crude homogenates of individuals of six species of cereal aphids (Sitobion avenae (F.), S. fragariae (Wlk.), Metopolophium dirhodum (Wlk.), M. festucae (Theo.), Rhopalosiphum padi (L.) and R. maidis (Fitch)) are described. The value of the techniques and banding patterns to taxonomic and population genetic studies of these and other aphid species are briefly discussed. With the six species, it was possible to separate the different genera as well as individual species within genera. The enzymes found to be most useful for inter–generic and/or -specific separations were adenylate kinase (AK), esterase (EST), glucose-6-phosphate dehydrogenase (G-6-PDH), hexokinase (HK), malate dehydrogenase (MDH), peptidase (PEP), phosphatase (PHOS), phosphoglucomutase (PMG), 6-phosphogluconate dehydrogenase (6-PGD) and sorbitol dehydrogenase (SORDH), whilst glutamate oxaloacetate transaminase (GOT), α-glycerophosphate dehydrogenase (α-GPD), malic enzyme (ME) and peroxidase (POD) were of relatively little taxonomic use. There were no banding pattern differences between the various morphs of S. avenae (first to fourth-instar nymphs, apterous and alate adults using the 14 enzymes.