The reaction products from the radically initiated grafting of specifically C-13-enriched maleic anhydride ([2,3-C-13(2)]MA) Onto polyethene, isotactic polypropene and ethene-propene copolymers in the melt and in solution are investigated using noise-decoupled and 1D inadequate C-13 NMR spectroscopy. The sites of attachment and the structures of the grafts depend oil (co)polymer composition. In random EPM, MA attaches to methylene and methine carbons in the backbone. In alternating EPM, MA attaches solely to polymer methines, indicating that (CH2)(m) seguences with m > 3 are needed for MA attachment to backbone methylene carbons. In the copolymers and in IPP, grafts are single succinic anhydride rings; in HDPE and LDPE short MA oligomers are also present. In polyolefins containing polypropene sequences, chain scission can yield structures in which the anhydride ring is attached to the chain terminus via a fully substituted double bond.