Polyfunctional protein PML contributes significantly to the vital activity of the cell. Eleven isoforms of PML differ from one another in their C-terminal domain. Despite intensive research into the protein, the role of the isoforms in cellular processes remains obscure. In addition, the literature contains various names for isoforms. The goal of this work is to review the structure of the PML gene, variants of alternative splicing of mRNA, and domain organization of corresponding protein forms. PML isoforms are classified and the functional specificity of each PML isoform is characterized as follows: contribution to gene transcription, contribution to cell apoptosis, cell growth, immune response, and the formation of nuclear bodies. © 2009 Allerton Press, Inc.