The study objectives were to characterize the morphology of the parasitic forms and describe the prevalence and intensity of Haemogregarina spp. in a population of the turtle Podocnemis unifilis as well as to examine the relationships between parasitism and turtle variables such as gender, size, and weight. Samples were taken in the Tapajós and Jamanxim rivers, Itaituba, Pará state, Brazil. Blood was collected from the tail vein of 72 P. unifilis specimens, including 35 males, 36 females, and one unsexed juvenile. The prevalence of Haemogregarina spp. was 98% (n = 71). The mean parasite intensity of Haemogregarina spp. was 118 (1-582) parasites/2000 blood cells (6%). There was no significant difference in the mean parasite intensity between male (137.68 ± 121.8, n = 35) and female turtles (101.42 ± 123.59, n = 35). There was no relationship between parasite intensity and carapace length. Although the relationship between parasite intensity and host body weight was significant, the relationship was weak. This is the first study on Haemogregarina parasitism with a relatively high number of turtles in Brazil.