Tomato breeders have hitherto selected for yield, uniformity and disease resistance rather than for internal qualities such as taste that depend on appropriate amounts and proportions of many different constituents. In order to improve internal quality it is necessary to find balanced donor parents with high contents of these individual constituents in order to develop this strategy. A methodology to evaluate all constituents together is also necessary. This work characterizes and classifies accessions of Lycopersicon to assist the selection of parents for several internal qualities. Thirty-eight accessions of L. esculentum, L. pimpinellifolium, L. hirsutum, L. pennellii and L. peruvianum have been studied, and their taste and vitamin C content characteristics have been measured. Some of the variables studied are complex since many chemical constituents are involved (pH, °Brix (SSC), titratable acidity), whereas other variables are individual constituents (vitamin C, oxalic acid, malic acid, citric acid, fructose, glucose and sucrose). Therefore, individual taste components in Lycopersicon accessions have been analysed by using precise analytical techniques (capillary zone electrophoresis) and statistical methods (principal component, cluster and GGE biplot analyses) for comparisons to be made not only among these, but also among controls (four breeding lines and one commercial hybrid). All analyses performed have allowed both for a good classification and for a selection of materials to be made. Two L. pimpinellifolium accessions are very interesting to use as donor parents in the first steps of tomato taste breeding programmes, since they are balanced and have shown three times the taste intensity of controls. Furthermore, characterization by individual constituents (citric, malic, oxalic and ascorbic acids, glucose, fructose, sucrose, etc.) has been found to be a precise tool to classify and select Lycopersicon germplasm for internal quality attributes.