SUMMARY1Paragonimiasis is a trematode infestation involving mainly the lungs.2The intermediate hosts are freshwater snails, crabs and crayfish.3The disease is endemic along the Eastern Pacific Coast.4In the lung the parasites form thin walled cysts with surrounding fibrosis, complicated by lung infection, abscess formation and bronchiectasis and pleural involvement is common.5Pulmonary lesions are evidenced clinically by the presence of slight cough with rusty sputum.6In 25% of cases there are intracranial lesions often with signs of increased intracranial pressure and these have a bad prognosis.7Diagnosis is effected by the radiological evidence and by the demonstration of the presence of ova in the sputum or faeces.8The radiographic appearances in the lungs comprise:(a). thin walled cysts.(b). local fibrosis.(c). reactive exudation.(d). small areas of consolidation with possible abscess formation.(e). bronchiectasis.(f). bilateral pleural reaction, and(g). pleural effusion.9Radiographic examination of the skull may show calcified cysts, enlargement of the pituitary fossa and other signs suggestive of hydrocephalus.10Ventriculography may show the ventricles dilated and displaced.11Prophylaxis consists in boiling crabs and crayfish before handling and eating.12There is no specific medical treatment. Surgery should be considered for localised chronic pulmonary complications and for intracr