1 - The stools o/ 2.666 individuais were examined (workers and officeholders of two industrial companies located in the states of Guanabara and Rio de Janeiro, Brasil); 2 - 1941 individuais, or 72,80%, were found parasitized by one or more worms; the stools of the remaining 725 (27,20%) yielded negative results; 3 - A complete hemogram was made of each of the 2.666 individuals; the eosinophiles rate was used - the use of this rate, in association vríth stool examinations, being the main object of this work; 4 - Table A shows how many times each worm was observed, and also the percentages. Despite the non-epidemiological character of this work, it was found that 46,81% were infested by Trichuris trichiura; 23,85% by Strongyloides stercoralis; 22,46% by Necator americanus and/or Ancylostoma duodenale; 20,51% by Ascaris lumbricoides; 1,65% by Schistosoma mansoni; 0,67% by Enterobius vermicularis; 0,26% by Taenia solium or T. saginata; and 0,11% by Hymenolepis nana; 5 - Stool examinations were carried out by the methods of Faust (or Ritchie), Willis, Baermann and sedimentation; 6 - Relative or percent values of eosinophilia were recorded, a rate of 5% or higher being considered as hypereosinophilia (Eo > 5%); 7 - Factors which give rise to oscillations in normal eosinophilia, such as age, race, hours of the nycthemer, physical factors, sex, chemical factors, and others, were concisely considered; 8 - A fuller treatment was given to the differences between parasitic and non-parasitic hypereosoniphilia, wtth emphasis on the dynamics of eosinophilia as given by the Lavier curve; 9 - The 2.666 cases were distributed according to the different degrees of eosinophilia. Graphs and curves were drawn showing the distribution of each worm and its associations; 10 - In order to properly explain the subject, an eosinophilic index was set up. This index is defined as the ratio between the number of cases with Eo > 5% in a given group, and the number of cases in the same group with Eo < 5%. The total number of positive cases yields the "average eosinophilic index", while the total number of negative cases yields the "residual eosinophilic index" 11 - By establishing the eosinophilic index it is possible to evaluate the eosinophilogenic capacity of each isolated worm and its associations; 12 - Special attention was given to the problems raised by the existence of hypereosinophilia in cases of negative coprological test for worms; several biological features of the subject were reviewed; 13 - Another question of great clinical importance explained in this work is that of the occurence of cases of parasitism by worms, without hypereosinophilia. The author, based on data of his own and on other data taken from the literature on the subject, discusses the physiopathology of eosinopoiesis in helminthiases and puts forward an interpretation for this as yet not fully explained fact.