Complementary and genomic clones encoding the mRNA and gene for a protein in the Syrian hamster that is highly homologous to C-reactive protein (CRP) have been isolated and studied. Coding sequence of the genomic clone is identical with that of the cDNA clone and predicts a mature protein of 206 amino acids and a 19 amino acid signal peptide. The single intron is 217 base pairs long and contains a short repetitive (GT)n motif. RNA blot analysis demonstrates that mRNA for hamster CRP is ~2.0 kb long, and unlike the closely related pentraxin female protein (FP), expression of this mRNA is not affected by the gender of the animal and accumulates equally in males and females during inflammation. In vivo administration of interleukin 1, interleukin 6, and tumor necrosis factor induces accumulation of hepatic CRP mRNA, and the acute-phase alterations in CRP mRNA levels arise as a result of enhanced gene transcription.