Trypsin inhibitors from four species of shrimp, P. vannamei, P. monodon, P. stylirostris, and P. californiensis were characterized by test tube and electrophoretic assays. Inhibitors in the four phylogenetically related species showed different inhibitory capacity and specificity for orthologous trypsins. Inhibitors from P. californiensis showed a broader inhibitory capacity. Shrimp inhibitors inhibited cod trypsin, but not porcine or bovine trypsin, and subtilisin. The inhibitor from P. vannamei was stable at a wide range of pH and temperature. Results suggest that endogenous inhibitors for trypsin are ubiquitous in the penaeids. Cette etude caracterise les inhibiteurs de la trypsine de quatre especes de crevettes, Penaeus vannamei, P. monodon, P. stylirostris, et P. californiensis. Les inhibiteurs de ces especes genetiquement proches montrent des capacites et des specifites differentes pour des trypsines orthologues (enzymes homologues de differentes especes). Les inhibiteurs de P. californiensis montrent une capacite inhibitrice plus large.