Intrapopulational tooth striation variability has been studied in a sample of 99 individuals from the medieval agriculturalist population of La Olmeda (Palencia, Spain). The number, length, and orientation of all observed striations were recorded using a scanning electron microscope and an image analyzer system. Tooth striations were observed at 100 × magnification on the buccal surface of Pm4 and M1 teeth. The results obtained for the adult age group indicate that the buccal striation pattern is a characteristic trait which does not vary significantly among teeth for each individual. Agegroup variability suggests that buccal tooth striations accumulate over quite long periods of time. The characteristic striation pattern for the population is completely attained in the subadult age group. For the analyzed population, seasonal changes in dietary habits apparently did not affect the buccal striation pattern. Weaning of children in the population from La Olmeda seems to have occurred long before 2–5 years of age. Infants had a highly abrasive diet, and subadult and adult individuals would have had a slightly softer diet, perhaps due to a higher meat intake. The buccal striation pattern as a dietary indicator seems to be of great reliability, allowing for quantitative analysis of intrapopulation and interpopulation variability. © 1994 Wiley-Liss, Inc.