Diffusion tensor imaging (DTI) has previously shown compromised white matter integrity in frontotemporal white matter fibers in patients with schizophrenia, as indicated by reduced fractional anisotropy (FA). In the present study we investigated whether reduced white matter FA is also present in relatives of individuals with schizophrenia who are at high risk (HR) for genetic reasons. Twenty-two HR subjects, 31 patients with schizophrenia and 51 control subjects underwent DTI. We compared FA between the three groups in the cingulum cingulate gyri, the uncinate and the arcuate fasciculi and the anterior limb of the internal capsules (ALIC). A voxel-based analysis showed lower FA in patients with schizophrenia compared to controls in left and right uncinate (p<0.03), the left arcuate (p<0.03) and left and right ALIC (p<0.01). Using an automatic region-of-interest analysis, less sensitive to potential misregistration errors, produced essentially the same results, as well as reduced FA of the ALIC in the HR group compared to controls (p<0.05). This study replicates previous findings showing lower FA in frontotemporal white matter fibers of schizophrenia patients. We also found reduced FA in the ALIC of both patients and subjects at high risk of schizophrenia when compared to controls. This may be a possible indicator of the higher vulnerability of relatives to develop the disorder.