Protein quality of shrimp waste meal (SWM) was assessed in a balanced experiment with rats. Thirty rats were randomly divided into 5 equal treatment groups of 6 rats, kept in individual perforated perspex cages and fed 4 different 10% protein diets consisting of (1) fish meal (FM), (2) SWM, (3) SWM + lysine + methionine, (4) SWM + methionine and (5) a nitrogen-free basal diet. SWM was made up of (g kg(-1)): 394.0 crude protein, 123.0 crude fibre, 26.8 fat, 140.0 ash, 98.2 chitin, with 10.58 MJ/kg metabolizable energy. Protein efficiency ratio, net protein retention and net protein utilization were best (P < 0.05) for rats on the FM diet, while amino acid supplementation improved these parameters for SWM. SWM reduced (P < 0.05) the relative weights of lungs, liver and intestine. Rats fed the SWM diet had lower (P < 0.05) plasma urea, protein and albumin, and supplementation of these diets with amino acids did not significantly improve these traits; Plasma Na+, K+, Cl- and HCO3- were increased (P < 0.05) in rats fed SWM. Plasma enzymes (GOT, GPT, GGT) increased (P < 0.05) with amino acid supplementation of SWM diets. The results showed that the protein quality of SWM is inferior to that of FM, but that supplemental methionine and lysine in SWM diets improved the quality of the protein.