Transgenic wheat plants without the selectable marker gene were obtained either in the presence or in the absence of selective pressure during the transformation protocol. When using hygromycin as selective agent in a co-transformation experiment involving a mixture of plasmids pGL2, containing the hpt gene, and pAI1Gus, containing the uidA gene, 3 out of 19 transgenic wheat plants had the uidA gene alone as shown by Southern blots. The gene was transmitted to the progeny following Mendelian rules. Segregation and loss of the selectable marker gene was also found in three out of six events from other experiments where high-molecular-weight glutenin genes were expressed or over-expressed. On the other hand, in 7 experiments where no selective pressure was applied and that involved 1016 bombarded explants, 23 transgenic wheat plants were obtained. The uidA gene was stably integrated as suggested by its transmission to the progeny.