In the children from Liberia and one woman from Guinea an infection with the lung fluke Paragonimus uterobilateralis was diagnosed, being the first cases of human paragonimiasis recorded in these two West African countries. Species determination was based on measurements and morphological structure of the parasite ova isolated from sputum and stool of the patients, and supported by biological and epidemiological evidence of the occurrence of this parasite species in natural animal hosts and P. uterobilateralis--metacercariae in freshwater crab populations in various parts of Liberia.