AbstractWe study the magnetic response of mesoscopic quantum dots in the ballistic regime where the mean free pathleis larger that the sizeLof the sample, yet smaller thanL(KFL)d−1. In this regime, disorder plays an important role. Employing a semiclassical picture we calculate the contribution of long tranjectories which are strongly affected by static disorder and which differ sharply from those of clean systems. In the case of a magnetic field, they give rise to a large linear paramagnetic susceptibility (which is disorder independent), whose magnitude is in agreement with recent experimental results. In the case of a Aharonov‐Bohm flux, the susceptibility is disorder dependent and is proportional to the mean free path as in the diffusive regime. We also discuss the corresponding non‐linear susceptibil