The second autopsy case of microlithiasis alveolaris pulmonum in our country was discussed. This case had no familial back‐ground or genetic predisposition for the disease and followed an almost asymptomatic course for 13 years since abnormal shadow of chest was revealed radio‐logically.Of interest in this case in the deposition observed microscopically of the same substance in alveolar walls or in the interstitium as the ground substance of intra‐alveolar microlith, which was probably responsible for the irregular elas