Two case histories are described of pleural and anterior mediastinal fibrosis presenting as a continuous fibrotic process with thick parietal pleural plaques extending from one pleura to the contralateral pleura through the retrosternal area, and with retroperitoneal fibrosis. Follow-up over 4 years in one case demonstrated rapid progression of disease, with pleural fibrosis preceding retrosternal and retroperitoneal fibrosis. Histopathological analysis in both cases showed non-tumoral fibrosis with broad fibrous bundles surrounding fibroblasts (and lymphocytes in one case). Possible causes such as infections and exposure to ergot derivatives were excluded. Both patients had been slightly or moderately exposed to asbestos. These cases represent an unusual new presentation of pleural and retrosternal fibrosis extending beyond the anatomical structures and associated with retroperitoneal fibrosis.