Bioneedles are small hollow mini implants fabricated from biodegradable polymers which can be filled with antigen. Bioneedles can be used for vaccination without syringes and needles. Formulations have been prepared containing tetanus toxoid with and without aluminum phosphate. Stability and immunogenicity of Bioneedles were compared with liquid formulations. The antigen, when formulated in Bioneedles, retained fully its antigenicity up to 60 degrees C for 1 week whereas the antigen, in its liquid form, lost all activity at 60 degrees C after 1 week. After 3 weeks at 60 degrees C, a recovery of 60% was still found in the Bioneedles. Mice injected with Bioneedles with adjuvanted tetanus toxoid showed a comparable functional antibody response to the group receiving conventional liquid injections. This response was achieved with a four times lower antigen concentration when using the Bioneedles compared to the regular injections. We conclude that Bioneedles are good alternatives for injections using needles and syringes.