Conflicting results have been reported on the use of the steatocrit to measure fecal fat excretion. Aiming to assess the reliability of this method and its usefulness in the diagnosis of intestinal enteropathies, we measured the steatocrit in 747 healthy children and 442 children with diarrhea grouped according to diagnosis. The steatocrit was found to correlate strictly (r = 0.93) with the chemical measurement of fecal fat. Reference values and ranges were established. The maximal steatocrit was observed in neonates; afterwards, it progressively decreased to an undetectable level in children older than 2 years of age. A steatocrit abnormally high for age was found in 20% of patients with acute diarrhea and in 53% of those with chronic diarrhea. All celiac patients with a gluten-containing diet showed a marked increase of steatocrit. We conclude that the steatocrit is a reliable and easy-to-perform test, which quickly provides valuable information in the diagnostic workup of the child with diarrhea.