Gene silencing is associated with heritable changes in gene expression which occur without changes in DNA sequence. In eukaryotes these phenomena are common and control important processes, such as development, imprinting, viral and transposon sequence silencing, as well as transgene silencing. Among the epigenetic events, paramutation occurs when a silenced allele (named paramutagenic) is able to silence another allele (paramutable) in Trans and this change is heritable. These behaviors are recognized by non-Mendelian inheritance patterns that are found independently of chromosome transmission ratio distortions and, at least in plants, in the absence of parent-of-origin effects. Paramutations are associated with repeated sequences in Z. mays, D. melanogaster and possibly in mammals, and are recognized when changes occur at regulatory regions of specific genes affecting discernible traits. In the 1950s, Alexander Brink described for the first time the phenomenon of paramutation, occurring in maize at the colored1 (r1) gene. Paramutation and paramutation-like interactions have been discovered in other plants and animals, suggesting that they may underlie important mechanisms for gene expression. The molecular bases of these phenomena are unknown. However in some cases, the event of paramutation has been correlated with changes in DNA methylation, chromatin structure and recently several studies suggest that RNA could play a fundamental role. The meaning of paramutation in the life cycle and in evolution remains to be determined even though we might conjecture that this phenomenon could be involved in a fast heritability of favourable epigenetic states across generations in a non-Mendelian way.