Copolymers of poly(3-hydroxy-nonanoate), PHN, with methyl methacrylate, MMA, were prepared using Co-60-gamma irradiator. The bulk solutions of PHN in MMA were prepared at different PHN feed concentration and they were irradiated to 8.5 kGy at room temperature. Polymer fractions obtained by solvent-nonsolvent fractional precipitation were carefully characterized using gel permeation chromatography (GPC), nuclear magnetic resonance spectroscopy (NMR), and thermal gravimetric analysis (TGA) techniques. High copolymerization yield was observed and the copolymer compositions obtained from the TGA measurements were consistent with the NMR results. PHN contents of the copolymer samples changed from 5 to 35 wt.-%. The strain at break and tensile strength values of copolymers were between the values of their respective homopolymers. It was observed that pure copolymer samples showed up to 13% strain at break.