Nutritional utilisation of legumes is of great interest because they contain important amounts of protein and other nutrients. Thus, feeding animals with peas (Pisum sativumL.) reduced growth performance and the relative contribution to body weight of liver (P<0.001), muscle (P<0.001) and spleen (P<0.01). The assessment of protein quality by conventional methods revealed that, as compared with casein as the control protein, those animals fed on the legume diet showed lower nitrogen retention (P<0.001), biological value (P<0.001), net protein utilisation (P<0.001) and protein digestibility (P<90.001). Finally, the measurement of hormonal dietary induced changes pointed out a reduction in the values of insulin (P<0.001), IGF-I (P<0.001), thyroxine (P<0.05) and corticosterone (P<0.001) in the legume fed animals as compared with controls. This response appears to reflect a metabolic adaptation to the diet, in which protein quality as well as some antinutritional factors, such as lectins, saponins, phytates, tannins, enzyme inhibitors, occurring in peas may be involved.