For eleven months a pathologic analysis was performed at Cartagenera de Acuacultura Ltda.’s farm, with two species of peneid shrimps: Litopenaeus vannamei Boone, 1931 and L. stylirostris Stimpson, 1984, which were sampled from twenty-two different pools in different times of the year, in order to find out if the general pathology was independent of the parasitism for the protozoa Gregarines and according to the to determinate the incidence of this parasite in the development of shrimps. The total amount of shrimps that were examined was 3,405, and Litopenaeus stylirostris showed a larger number of Gregarines per intestine (94). It was also noticed that the specie L. vannamei showed a higher sensibility to cyclic changes to be parasitic. This parasitism showed up to be independent from any other clinic sign that the examined individuals showed: however, a relation was found between parasitism and behaviour of salinity, since that when showing less stability (rainy season), a larger degree of infestation was observed, which did not happen with the other physical and chemical parameters tested (dissolved oxygen, temperature, and pH).