We have cloned two cDNAs from the pituitary gland of blue gourami (Trichogaster trichopterus), coding for the beta subunits of the gonadotropin hormones GtH-I and GtH-II. The two cDNAs were sequenced and subjected to sequence analysis. We have found that the deduced amino acid sequences of both cDNAs were most similar to their striped bass counterparts. The beta GtH-I subunits of blue gourami and striped bass shared 73% of their residues, and the beta GtH-II subunits 84%.The cloning of the cDNAs of beta GtH-I and beta GtH-II has enabled us to measure the expression of their respective mRNAs in the pituitaries of female blue gourami at different stages of the reproductive cycle. The highest levels of beta GtH-I and beta GtH-II mRNA were found in specimens classified as high vitellogenic and in females that were at the final stages of oocyte maturation.