Examination of bovine satellite DNA I methylation within CpG dinucleotides has been made by restriction analysis. It is shown that variations in the methylation patterns occur between different tissues (brain, liver, thymus and sperm) . Some of the 8 Hpa II sites present per repeat are clearly undermethylated in sperm as compared to other tissues. Methylation is considered therefore, as a highly specific event. It is also shown that there is a spatial specificity in the methylation pattern of the 3 Hha I sites in all tissues. These results are discussed in the light of methylation and satellite DNA functions.