Research in buccal microwear started in the late 1980s with a hypothesis relating striation length by orientation with the proportion of plant and meat foods in the diet. Such relationship has proven to be more complex than initially thought, with the density of striations being one of the most discriminating variables on the enamel surface. Significant differences in buccal microwear pattern have been observed both within populations, by age and sex, and between groups. Hunter-gatherer modern humans clearly differ in their buccal microwear, with strictly carnivorous populations showing a low density and short striations. The analyses of the buccal microwear of fossil humans have suggested that modern humans' microwear models may not be appropriate to infer diet in ancient populations. However, significant between-group differences have also been demonstrated in these populations, though the ecological, cultural and biological nature of such differences still needs to be ascertained. Buccal microwear has great potential to human evolutionary research. Informative, rather than large, samples need to be analysed. More than ever, the hypotheses to be tested are of major importance. Microwear research needs to thrive through a methodological revolution, so the years to come will be of special interest for human evolutionary research.