A process for preparing plastic wood which comprises impregnating wood with a mixture containing (1) an organopolysiloxane having groups which are capable of condensation and/or containing SiC-bonded alkenyl group having an average molecular weight of at least 500 when the organopolysiloxane contains from 0.5 to 1.89 SiC-bonded organic radicals for each silicon atom and when the organopolysiloxane (1) contains from 1.90 to 2 SiC-bonded organic radicals for each silicon atom, then the average molecular weight is at least 20,000 and (2) an organic silicon compound having at least three groups which are capable of condensation and/or atoms capable of condensation and a maximum of 10 silicon atoms per molecule; and other substances if desired; and thereafter crosslinking the organopolysiloxane (1) having groups capable of condensation and/or containing SiC-bonded alkenyl groups, which is present in the wood.