The present study was aimed at evaluating whether Mycoplasma pneumoniae (MP) pneumonia presents with typical X-ray patterns which can help its diagnosis. The chest films of 32 adult patients with serologically proven MP infections were reviewed. Confluent or patchy consolidation was the most common finding (66% of patients), interstitial involvement was much less frequent (19%), and so were "mixed" patterns (15%). Unilateral involvement was common (69%), the lower lobes were frequently involved (52%) and in 78% of cases only one lobe was affected. Pleural fluid (40%) and atelectasis (31%) were commonly seen, while hilar adenopathy was rare (9%). In substantial agreement with previous studies, no distinctive X-ray pattern of MP pneumonia was found and marked differences were seen to exist in its radiographic appearance. Despite these obstacles, some characteristic X-ray findings were suggestive of MP pneumonia: diffuse/localized interstitial involvement appeared to be the most helpful sign, in combination with clinical and epidemiologic data. On the contrary, patchy and acinar consolidations are slightly suggestive of MP etiology.