This paper records the discovery of a new pathogenic lung fluke Paragonimus hueit'ungensis sp. nov. in Hueit'ung County of Hunan Province. The salient features of the adults of this lung fluke, its first and second intermediate hosts, rediae, cercariae, metacercariae and the results of feeding experiments on laboratory animals (albino rats, cats, and dogs) are described and compared with the relevant species of lung flukes already known. Biopsies of the migratory subcutaneous nodules done in 2 pediatric cases seen in the endemic area of Hueit'ung County have both shown the presence of immature adolescent lung flukes, whose morphological features agree in general with those obtained through feeding experiments in laboratory animals. But the reproductive organs of these biopsied adolescent flukes are poorly developed; and they do not produce eggs in the human body where they appear to migrate blindly from one place to another, indicating that man is not a suitable final host for this parasite, in spite of its pathogenic implications. Hence one has to be careful not to confuse clinical cases of this new form of paragonimiasis with those due to paragonimiasis szech'uanensis. Studies on the different aspects of this new lung fluke are obviously of practical importance in the early diagnosis, treatment, and prevention of the disease in the localities concerned.