The location and magnitude of fractional anisotropy (FA) reduction measured by diffusion tensor imaging (DTI) is not consistent across neuroHIV studies probably because of the heterogeneity of clinical and neurocognitive characteristics in selected HIV-infected (HIV+) samples. As such there is a lack of understanding of the level of white matter damage/integrity in treated and chronic HIV infection and the role of key demographics, laboratory and treatment effects that are important factors to consider in the HIV population.The study sample included 122 men of whom 40 were HIV- and 82 were HIV+ with comparable demographics and life styles (Table 1). The study was designed to recruit chronic HIV+ participants (Table 2). HIV-associated neurocognitive disorder (HAND) was classified using standard criteria (Table 2) 1. DWI was acquired on a 3T Achieva TX (Philips Medical Systems, Best, The Netherlands) with an 8-channel SENSE head coil. Images were acquired in the axial plane using a single-shot EPI sequence optimised for use on this scanner (TR/TE: short/68ms; b=1000s/mm2; 2.5 mm isotropic resolution; flip angle: 90°; FOV 240x240; 55 slices) in 32 diffusion gradient directions, plus one a b0 for diffusion tensor fitting. DTI processing: data were extracted from DWI in Itrack IDL 2. For each voxel, tensor eigenvectors and corresponding eigenvalues were computed, and FA values derived. FA maps were then fed into standard tract-based spatial statistics (TBSS) skeletonization 3. Next each person’s FA data was projected onto ENIGMA standard space 4. Then, TBSS skeletons were segmented according to the Johns Hopkins ICBM-DTI-81 atlas, average FA values were computed in 12 selected regions of interest (Figure 1; ROI, right and left ROI were averaged, as there were no significant differences) primarily including brain areas known to be associated with HIV-related brain injury (Genu, body and Splenium of corpus callosum [GCC, BCC, SCC], Fornix [FX] anterior and posterior limb of internal capsule [ALIC, PLIC], anterior and superior corona radiata (ACR, SCR), external capsule [EC], Cingulum [CG], Superior longitudinal fasciculus [SLF], Uncinate fasciculus (UNC]). Statistical analyses: Averaged FA values in the 12 ROI were compared between HIV- and HIV+ sample using MANOVA and a mean response. Effects of age and education were tested using a linear regression (and an interaction term). Effects of HIV disease and treatment markers were tested using univariate and multivariate regression. Neurocognitive functioning was evaluated using three clinically relevant groupings: HAND versus no HAND; ANI, versus MND+HAD, versus NP-normal, and HAD versus no HAD. Associations with FA values were tested with ANOVA and Dunnett’s control or t-test as appropriate. P-value for significance was set at p<.05.There was no between-group difference in FA values across the 12 ROI (p=.63, Figure 2). A negative age effect was found in the ACR (p<.009), EC (p<.02); and FX (p<.001). There was only a trend for an age and HIV status interaction in the CG (p=.07, Std Beta=.18) where HIV+ cases had lower FA as a function of age. There were interactions of HIV status and education in the FX (p<.03, Std Beta=.21; as function of education lower FA in HIV+ versus higher FA in HIV-), the SCR, and SLF (p<.03, Std Beta=-.22; as function of education lower FA in HIV- versus higher FA in HIV+). Univariate analyses, in the HIV+ group only, showed that CD4-T cells count was associated with higher FA in the ACR (r=.30; p=.0006); FX (r=.25; p=.03), and SLF (r=.25; p=.03). HIV duration was associated with lower FA in the FX (r=-.31; p=.004) and higher FA in the SCR (r=.25; p=.03). CART duration (r=.27; p=.01) was associated with higher FA in the ACR (r=.27; p=.01) . CPE rank score was associated with higher FA in the ALIC (r=.38; p=.0004) and PLIC (r=.23; p=.04), and GCC (r=.23; p=.04). Multivariate model showed that each biomarker and treatment effects were independently associated with FA values. Individuals with MND+HAD had lower FA values in the CG (p=.04), FX (p=.007) compared to NP-normal and ANI cases. HAND cases had lower FA in the FX compared to the no HAND cases (p=.04). HAD cases had lower FA in the SCR compared to the no HAD cases (p=.02).We present the first evidence for complex brain repair processes in treated and chronic HIV infection arguing for careful multilevel characterization of HIV+ samples in neuroHIV DTI studies. The association of neurocognitive function with FA suggests ongoing vulnerability despite highly successful treatment.