This paper contributes to the discussion of Amazonian systems of nominal classification by providing the first description of the system of Uitoto, spoken in the Colombian Amazon. Two gender markers and a set of more than 100 classifiers, most of them denoting physical properties, are described with respect to their distribution and eventual patterns of agreement, their degree of grammaticalization, and their discursive function. Special attention is given to the relation between classifiers and nouns and to the formation of pro‐forms with classifiers, stressing the importance of classifiers in the lexical genesis of the language.