This review covers almost 30 Pt(II) complexes of the composition Pt(eta(3)-(PXP2)-X-1-P-1)(Y), (X-1 = BL, SL, or SiL), (Y = H, OL, NL, CL, Cl, PL, or I) and Pt(eta(3)-(PPSi1)-P-1-Si-2)(CH3). Heterotridentate ligands form six types of metallocyclic rings: (PCNBNCP2)-C-1-N-1, (PC2SC2P2)-C-1-C-1, (PC2SiC2P2)-C-1-C-1, (most common), (PCNSiNCP2)-C-1-N-1, and (PC3SiC3P2)-C-1-C-1 with common B-1, S-1, or Si-1 atoms. In (PC2PC3Si1)-C-1-C-2 the P-2 atom is common. The structural data (Pt-L, L-Pt-L) are analyzed and discussed with an attention to the distortion of a square-planar geometry about Pt(II) atoms as well as trans-influence. The sum of Pt-L(x4) bond distances growing with covalent radius of the X-1 and Y atoms.