The isotope ratio in metal deposits obtained by sputtering a flat target at low ion energy (100 eV) under normal ion incidence is a function of the ejection angle. The lighter isotope (s) are enriched in the direction normal to the target surface as result of ’’reflective collisions’’ which occur when an atom collides with one of heavier mass underneath. Experimental results are presented for Cu(63‐65) and the seven Mo isotopes.