Brazilian poultry production is growing, mainly due to the cost and benefit that chicken meat provides. The importance of freerange chickens and the susceptibility, to which they are exposed, makes it necessary to know about gastrointestinal parasites and the consequences that large infections can cause for them as such as weight loss. The present study aimed to determine the occurrence of gastrointestinal parasites in free-range hens raised in an extensive regime in the municipality of Santa Rita, state of Maranhão, Brazil. The studied population was composed of adult chickens (Gallus gallus domesticus) acquired from slaughterhouses in the region. The gastrointestinal organs of each chicken were separated and subsequently conditioned in flasks containing Railliet and Henry's solution and sent to the laboratory, to be analyzed and processed. Of the 100 chickens examined, 227 specimens of helminthes were identified, with a frequency of 32.6% for nematodes and 67.4% for cestodes. Among the nematode the following parasites were identified: Ascaridia galli (27.03%); Heterakis gallinarum (48.65%) and Subulura spp. (24, 32%). Raillietina echinobothrida (100%) was the only cestoda identified. The average infection rate by species of parasite was 1.18 for A. galli, 2.22 for H. gallinarum, 1.06 for Subulura spp. and 9.00 for R. echinobothrida. It is concluded that free-range chickens are parasitized by nematodes and cestoda.