Variation in altitude seemed to have little influence upon the percentages of parasites. The small number of persons studied in Recuay may account for the observed variations in this instance. Dwarf tapeworm was especially frequent and the first hundred persons examined all carried Giardia lamblia, which gave the investigators the impression (later proved false) of having found a population with 100 per cent incidence of this infection. Heterodera seemed to increase with lower altitudes, perhaps due to the increased consumption of vegetables of the collard family. A high incidence of Ascaris was noted among the Quechua Indians as well as of Balantidium which was also frequent in the jail inmates. Hookworm was present in the outlanders in the jail and in the police force. Taenia was not as common as expected and only one case of Bodo and one of Enteromonas were found, both among the Vicos people, and one case of Haemonchus at Carhuas. Four cases of Isospora and five of unidentified species of intestinal nematodes were found irregularly distributed throughout the valley. No correlation between the parasite population of an individual and his eosinophile count was discovered.