Since October 1991 the AMBER technique has been used for the diagnosis of chest diseases in about 4,000 patients. The ability of this technique, compared with conventional methods, for demonstrating intrathoracic masses on p.a. views has been assessed. Amongst the patients there were 43 with coin lesions, 18 with hilar and 33 with mediastinal masses. ROC analysis showed the AMBER technique to be superior in demonstrating coin lesions (AMBER 0.92, conventional 0.85) and mediastinal masses (AMBER 0.89, conventional 0.73). There was a small, statistically not significant, disadvantage in the AMBER technique for demonstrating hilar masses (AMBER 0.80, conventional 0.84).