Protein myristoylation was first discovered in the catalytic subunit of adenosine 3', 5'-cyclic monophosphate-dependent protein kinase. Subsequently, various cellular and viral myristoylated proteins were detected. In each case, the myristoyl moiety was found in an amide linkage with the amino terminal glycine residue of the modified proteins. The biological functions of protein myristoylation of various cellular protein, oncogene product, and viral structural proteins have been studied by many biochemists. Two of the most throughly studies myristoylated proteins are the transforming protein of Rous sarcoma virus, pp60^v-src, and the proto-oncogene product, pp60^v-src. Deletion, modification of the first 14 NH₂-terminal amino acid of pp60^v-src, or chemical antimyristoylation of the protein with N-myristoyl glycinal diethylacetal dose not affect intrinsic tyrosine src-kinase activity, but prevents myristoylation and membrane association, and abolishes the transforming activity of the protein. Protein myristoylations of some viral structural proteins were also studied by many investigators, and X-ray crystallographic studies of poliovirus suggest that myristate moiety may play a central role in capside assembly. Recently, human immunodeficiency virus, HIV-I, prossesses a myristoylated p17^gag protein, which is proteolytically derived from the NH₂-terminus of a gag precursor protein, and its myristate moiety may be important for virus assembly. In this review, we detailed recent studies of the protein myristoylation in cellular regulation and virus proliferation.