The human insulin-like growth factors (IGFs) are important regulators of growth, which exert their functions via endocrine, paracrine and autocrine mechanisms of action. Structural analysis of the genes coding for IGF-I and -II has revealed that they have a complex exon-intron structure and possess multiple promoters. The expression of the IGF genes is regulated at the levels of transcription, RNA processing and translation. This review summarizes our current knowledge of the structure and expression of these genes.