1. mRNA isolated from larval Taenia crassiceps directs efficiently the synthesis of proteins in cell-free heterologous systems. 2. Part of the newly synthesized proteins in a reticulocyte system are precipitable by a rabbit antiserum against T. crassiceps proteins. 3. Analysis of the antiserum-protein dissociated complex by sodium dodecyl sulfate polyacrylamide gel electrophoresis indicates that most of the proteins synthesized are of low molecular weight (13,000-22,000) although a protein of mol. wt. 260,000 is also produced. 4. Whether the newly synthesized proteins which are precipitable by specific antisera correspond to parasite antigens or to proteins with closely antigenic similarities remains to be established.