The author studies the species Filariopsis barretoi (Travassos, 1921) parasite of Callithrix jacchus. It is the second reference of this parasite. The author gives an historic of the species since the original description by Travassos (1921). He adds new features to the original work and he also presents some pathological aspects of the worm in the lung's host. A new generic combination is proposed considering the presence of lips in the oral extremity, fact not mentioned in the original description by Travassos. The species now must be called Filariopsis barretoi (Travassos, 1921) Rego, 1974.