Background: The International Conference on Applications of Neuroimaging to Alcoholism was held at Yale University in New Haven, CT, in January 2004. The following is a brief summary of the contributions of five speakers who presented their work during the magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) session. Methods: This session addressed how MRI and DTI are used to assess macro- and microstructural brain alterations in alcoholism. Structural MRI methods can address regional gray and white matter volumetric/ morphometric abnormalities, and DTI methods can address microstructural disruptions of white matter tracts. These methods can be applied across the spectrum of alcoholism to elucidate distinct brain abnormalities underlying clinical subtypes, to disentangle brain volume deficits that precede, from those that follow, the onset of alcoholic drinking in chronic alcoholics, and to examine effects of prenatal alcohol exposures on brain development in children. The presentations highlighted recent scientific findings and methodological advances in these areas. Results: Disease-specific probabilistic atlases, designed to reflect the unique anatomy and physiology of particular clinical subpopulations, can be developed for alcoholism. Such an atlas can be used to identify efficiently patterns of altered structure or function in alcoholism and can guide algorithms for knowledge-based image analysis. DTI is sensitive to constraints on the random diffusion of water molecules in axons, allowing assessment of white matter tract integrity in neuropsychiatric diseases, including alcoholism. Recent MRI and DTI data were presented showing region-specific brain abnormalities at both macro- and microstructural levels that varied differentially according to sex, time of alcohol exposure in life, and alcoholism subtype. Conclusion: The International Conference on Applications of Neuroimaging to Alcoholism brought together leading experts in MRI and DTI techniques to discuss their applications to the study of alcoholism. The extant and new imaging technologies provide us with multiple modalities to study the brain in vivo. These noninvasive tools enable us to monitor the time course of alcohol effects on the brain and to characterize macro- and microstructural brain abnormalities across the full spectrum of alcoholism, including its precursors and its sequelae.