One hundred and three random complementary DNA clones representing rainbow trout intestine were par1i811y sequenced as an approach to analyze the transcribed sequences of its genome. Of the sequences generated, 60.0% of the ESTs were represented by 40 known genes. Thirty-five clones of unknown gene products potentially represented 34 novel genes. The most Bbundantly represented messages were the 28S ribosomal protein (6.5%) and beta actin (5.8%). The genes involved in ribosome formation (18%) accounted for the major gene expression. Development of EST panels representing the genes expressed in a particular tissue will be useful in determining the role of these genes in normal function and in response to developmental, hormonal, environmental and physiological changes.