1. The early history of F. osleri together with its world-wide distribution is discussed. 2. The various breeds of dogs affected are listed showing that most breeds have been affected at some stage. 3. The South African history is traced showing how some breeds and studs were infested. 4. The various symptoms found with infestation by F. osleri are enumerated. 5. The factors influencing the pathogenesis are mentioned and discussed. 6. All breeds of dogs of all ages are equally susceptible. Reasons for the seemingly greater susceptibility of the newly born puppies are advanced. 7. Both the macroscopic and microscopic lesions of F. osleri infestation are described. Mention is also made of the morphology of the parasite. 8. Diagnostic methods are dealt with and only the reliability of examination with a bronchoscope advocated. 9. The differential diagnosis of the condition and possible pitfalls in diagnosis are discussed. 10. Observations on the life cycle indicates this to be direct with no evidence of intra-uterine transmission. 11. Both sexes of the host animal are equally susceptible. 12. Infestation of the host is acquired at a very early age under natural conditions, the larvae being transported to the predilection site via the lymphatic system. Migration experiments are discussed in detail as is the morphology of the migrating larvae. 13. Histopathological changes observed in the lymph nodes, liver and lungs are described, the absence of eosinophiles especially being noteworthy. 14. Various chemotherapeutic agents are evaluated together with a description of a surgical technique for the removal of nodules. 15. A completely successful treatment consisting of a course of caparsolate sodium followed by intratracheal surgery is described and discussed. 16. The need for the possible re-classification of F. osleri in the light of the evidence advanced is suggested. 17. Prophylactic measures are listed.