Objective Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) is a hereditary small vessel disease responsible for an early onset cognitive impairment. Aim of our study was to test the cortical cholinergic innervation in CADASIL by short latency afferent inhibition (SAI) technique. Methods We applied SAI in ten CADASIL patients and in ten age-matched normal controls. SAI is a phenomenon observed on motor evoked potential when transcranial magnetic stimulation is delivered after a time ranging from 2 to 8ms longer than the time needed by the peripheral nerve afferent input to reach the somatosensory cortex. Results The amount of short latency afferent inhibition was significantly smaller in CADASIL patients than in controls (79.5±21.7% Vs 42.7±14.1% of test size; p <0.001, two tailed Mann–Whitney test). The mean resting motor threshold (RMT) was significantly lower in CADASIL patients than in controls (49.4±14.4% Vs 65.6±15.4%; p =0.02). Conclusions We demonstrated by SAI technique a central cholinergic impairment in CADASIL. Significance SAI could be used to evaluate the cholinergic dysfunction and potentially the efficacy of cholinomimetic therapy in CADASIL.