Abstract Efficiency of Agrobacterium mediated gene transfer was improved in rice by microprojectile pretreatment. Fertile transgenic plants were easily recovered using this protocol. Since an osmotic treatment is part of the bombardment protocol, we studied the effect of plasmolysis alone (i.e. without any microprojectiles) on transient expression of the gus gene transferred by Agrobacterium to precultured rice embryos. We report here for the first time that plasmolysis alone as a single pretreatment, yielded an even higher number of cells expressing the marker gene than the combination of microprojectile bombardment and osmotic treatment. This indicates that the effect of the osmoticum on gene transfer is independent from bombardment.