Starch gel electrophoresis was carried out on ten monosomic alien addition lines (MAALs) of Oryza officinalis (CC genome) in O. sativa (AA genome) at Punjab Agricultural University, Ludhiana, India during 1993–1995. The diploid progeny from MAALs were studied for possible gene transfer of isozyme genes. Analysis showed introgression for alleles of wild species for peroxidase, esterase and acid phosphatase isozymes in progeny of MAAL 2, esterase in MAAL 7 and acid phosphatase in MAAL 6, indicating partial homology between the two genomes. MAAL 2 yielded the highest number of recombinants. The potential of addition lines for alien gene transfer as well as for linkage mapping is discussed.