Gene duplication is considered to be a source of genetic information for the creation of new functions. The Arabidopsis thaliana genome sequence revealed that a majority of plant genes belong to gene families. Regarding the problem of genes involved in the genesis of novel organs or functions during evolution, the reconstitution of the evolutionary history of gene families is of critical importance. A comparison of the intron/exon gene structure may provide clues for the understanding of the evolutionary mechanisms underlying the genesis of gene families. An extensive study of A. thaliana genome showed that families of duplicated genes may be organized according to the number and/or density of intron and the diversity in gene structure. In this paper, we propose a genomic classification of several A. thaliana gene families based on introns in an evolutionary perspective.