Type VI collagen was immunolocalized in several soft connective tissues at the light and electron microscopic level. Positive labeling was found in all tissues examined, periodontal ligament, gingiva, mesenterium and periosteum. The labeled structures could be divided into 2 categories: microfibrils intermingling with collagen fibrils, and those that formed bundles (oxytalan fibres and elastin-associated microfibrils). Control sections incubated with antibody preabsorbed to purified type VI collagen, or with non-immune antibody, proved to be negative. Our observations indicate that the structural organization of type VI collagen varies from small microfibrillar structures associated with the collagen and elastin fibre systems to highly ordered parallel arrays of oxytalan bundles.