Russian adjectives, especially participles, can be used as nouns denoting people, e.g. bol′noj/bol′naja ‘(male/female) patient’ from bol′noj ‘sick’, učaščijsja/učaščajasja ‘(boy/girl) pupil’, participle from the verb učit′sja ‘to learn, study’. These are unusual in that they formally reflect the sex of their referent by means of inflectional morphology. Moreover, many surnames inflect like adjectives and they, too, inflect for gender: Mr. Puškin, Čexov, Tolstoj, Dostoevskij but Ms. Puškina, Čexova, Tolstaja, Dostoevskaja. Lexemes such as ‘patient, pupil’ are genuine nouns and not just adjectives modifying null nouns. The latter type do exist and have different properties from converted nouns. Converted nouns and adjectival surnames thus form systematic gender pairs which are forms of a single lexeme. However, gender is not conventionally regarded as an inflection category of the kind which induces word forms of lexemes in this way, rather it is an inherent ‘classificatory’ property of nouns. The paper discusses the peculiar nature of this type of inflectional marking and provides an explicit analysis of the construction. On the semantic side, nouns such as bol′noj, učaščijsja have a similar representation to that of a phrase person who is sick/studies and we effectively have an instance of the poorly researched phenomenon of de-phrasal word formation. On the morphosyntactic side, the lexical entry of the deadjectival noun or surname shares crucial properties with 3rd person pronouns. The analysis raises questions about the nature of lexical categories (especially ‘mixed categories’) and the structure of lexical entries generally.