Over the past ten years or so, the isozyme electrophoresis technique has been developed on rubber in the CIRAD laboratories. This technique, which was first used to study the genetic diversity of Hevea germplasm, proved particularly effective and was applied to other topics interesting for rubber breeding programmes : conformity clone testing, checking progeny legitimacy and studying open pollination. Compared to other molecular markers, isozymes are competitive as they combine reliability, easy use, moderate cost and powerful discrimination capacity. Thus, it remains a useful tool for plant breeders and is still currently used on a large scale.