Copolymerizations of ethylene with 10-undecen-1-ol, 10-undecenyl methyl ether, 10-undecenyl trimethyl silyl ether, and 1-undecene were performed with rac-ethylene-bis(l-indenyl)zirconium dichloride as a catalyst and methylaluminoxane as a cocatalyst. All three oxygen-functional comonomers copolymerized with ethylene, although the activity of the catalyst decreased considerably compared with the homopolymerization of ethylene. The conversions of the comonomers varied from 17 to 40%, depending on the amount of comonomer in the feed. Under the same conditions, the conversion of 1-undecene was 50-75%. The incorporation (0.7-3.6 mol %, depending on the feed) and the effect on the activity of the catalyst were on the same level for all the functional comonomers, which indicates that trimethylsilyl or methyl groups do not act as effective protecting groups for oxygen atoms. According to NMR and Fourier transform infrared analyses, the final functional group in the copolymers of the trimethylsilyl ether comonomer was hydroxyl. In contrast, the methyl ether group remained untouched in the copolymer, which suggests that the formation of aluminum alkoxides via a reaction with a cocatalyst is not a prerequisite for comonomer incorporation.