Micromechanical measurements have been performed with a beam bending based technique using an atomic force microscope (AFM). This technique combines a very high load resolution with a nanometric precision in the measurement of the cantilever deflection. It has been applied to the determination of the Young's modulus of different micromachined structures as polysilicon and β-SiC cantilever beams. This has required the previous calibration of the technique. The different characteristics of the analysed structures determined the need to use different AFM probes, being the optimum measuring condition achieved when both the probe and the beam have similar force constants. The results obtained show the ability of the proposed technique for the micromechanical assessment of miniaturised structures, which is required for development and optimisation of advanced micromachining technologies.