We recorded absorption and assimilation efficiencies of the shrimp Penaeus stylirostris fed an artificial diet containing radioactive ( 1 4 C) mussel flesh. Our experimental procedure coupled pulse chase design, compartmental analysis and analog modeling. It led to estimations of absorption (i.e. between 92.4 and 96.2%) which are in good agreement with similar digestibility data (regarding protein, lipid and carbohydrate) previously collected for the same species by using the Cr 2 O 3 method. This helps to establish the validity of this new approach which is potentially more sensitive due to the use of radioisotopes. The estimation of assimilation efficiency was 86.1%. Because of the coupling of compartmental analysis and analog modeling, this approach allows for an estimation of the whole CO 2 production following an experimental meal. This could be very valuable when applying oxidation methods to the study of amino acid requirements in shrimp.