White matter alterations are well-established in adult patients with psychosis. Yet less is known about alterations in early onset psychosis (EOP) during adolescence, especially whether antipsychotic medication might impact white matter microstructure in this sensitive phase. Here, we utilized Magnetic Resonance Imaging (MRI) in unmedicated and medicated adolescent EOP patients in comparison to healthy controls to examine the impact of antipsychotic medication status on indices of white matter microstructure. Twenty-two EOP patients (11 unmedicated) and 33 healthy controls, aged between 12-18 years, underwent 3T diffusion-weighted MRI. Using Tract-based Spatial Statistics, we calculate case-control differences in scalar diffusion measures, e.g. fractional anisotropy (FA), and investigated their association with antipsychotic medication. We replicated previous results from studies in EOP patients showing significantly decreased mean FA including the left genu of the corpus callosum, the left anterior corona radiata and the right superior longitudinal fasciculus in patients relative to healthy controls. Mean FA in the left anterior corona radiata was significantly predicted by antipsychotic medication status with higher FA values in medicated compared to unmedicated EOP patients. The increase in regional FA might be a first hint towards an early beneficial effect of antipsychotic medication on white matter microstructure in adolescent EOP patients.