Avian coccidiosis is a disease which causes important economic Iosses to avían production worldwide. The objective of this study were to determine the relationship between oocyst concentration in litter and grade of gut injury, as well as the íncidence of subclinical coccidiosis. A total of 216 birds were studied between April and June 1999, when temperatures and humidity fluctuated between 19-21ºC and 60-85%. Litter samples were collected using the double W method at days O, 7, 14, 21, 28, 35, 42 of the birds life, and processed utilising the modified McMaster method. Macroscopic and microscopic evaluation of intestinal lesions was made when halfthe birds (n=108) · weie sacrificed at 28 days of age, and the remainder (n=l08) at 35 days. Macroscopic injuries ofgrades +l and +2 were observed in 7.7% ofthe 28 day old birds and 4.3% ofthe 35 day old birds, while microscopic injuries were found in 48.8% and 42% ofthe 28 and 35 day old animals. Although the frequency of oocysts per gram of litter was greatest between days 28 and 42, the correlation with incidenceofmacro and microscopic lesions at days 28 (0.748)and 35 (0.432) was only moderate.