Human beta-amyloid (A beta) is believed to be one of the main components of Alzheimer's disease, so reduction of A beta is considered a key therapeutic target. Using Agrobacterium-mediated nuclear transformation, we generated transgenic tomatoes for A beta with tandem repeats. Integration of the human A beta gene into the tomato genome and its transcription were detected by PCR and Northern blot, respectively. Expression of the A beta protein was confirmed by western blot and ELISA, and then the transgenic tomato line expressing the highest protein level was selected for vaccination. Mice immunized orally with total soluble extracts from the transgenic tomato plants elicited an immune response after receiving a booster. The results indicate that tomato plants may provide a useful system for the production of human A beta antigen.