  K-band imaging of a sample of 21 radiogalaxies with z \sim 1.5 reveals the
existence of a statistical association of foreground galaxies with the
positions of the radiosources. The excess is detected within a 1' radius at a
high significance level (>99.8%). K-band light is a good tracer of stellar
mass, so this result indicates the existence of an association between
foreground mass perturbations and background radiosources, as expected from the
magnification bias effect, and confirms previous results obtained for other
high-z radio-loud AGN.
