The digital chest posterior-anterior roentgenograms of 42 healthy individuals were ranked twice (interval of at least 5 days) in the order of increasing lung parenchymal markings. The evaluations were made by three radiologists, two residents, a medical student and a radiographer. All observers regardless of their radiological experience showed good intraobserver correlations between their two subsequent rankings (p < 0.05-0.001). The interobserver agreement on rankings was generally poor, even if the radiologists were considered. Radiologic training seemed to eliminate the influence of false leading factors (the object's respiration and body constitution). "The golden standard of evaluation" (= the added-up rankings by the radiologists) did not correlate either with the patient's ages (19-54 years) or smoking habits (0-45 pack-years, mean 4.2).