1. Lysate is prepared from guinea-pig reticulocytes and its translation activity is compared both quantitatively and qualitatively with that found in rabbit reticulocyte lysates. 2. Guinea-pigs are comparatively resistant to acetylphenylhydrazine, a drug used to induce reticulocytosis in rabbits. 3. The characteristics and conditions for maximal translation activity in guinea-pig reticulocyte lysates are quite similar to those described for rabbit reticulocyte systems with the possible exception of the components necessary for providing high energy phosphate bonds. 4. Both rabbit globin and brome mosaic virus messenger RNAs direct protein synthesis in the guinea pig translation system with activity similar to that found in the rabbit system. 5. Translation products synthesized in the guinea-pig and rabbit systems and fluorographed following separation on sodium dodecyl sulfate-polyacrylamide demonstrate similar electrophoretic patterns and intensities.