The authors survey the textological and linguistic relevance of Croatian Church Slavonic for the study of Old Church Slavonic. In the field of textology there are at least three subsets of Croatian Church Slavonic texts which are important for palaeoslavistics: 1. translated texts which are not found in other Church Slavonic redactions, 2. texts which are known in a geographically limited area, 3. texts which are first attested in Croatian Church Slavonic. Linguistically, Croatian Church Slavonic has long been renowned for its conservatism. Archaic forms are to be found in grammar as well as in vocabulary. In morphology one could mention the archaic forms of the conditional, archaic aorists (root and primary sigmatic aorists), archaic case forms of substantives (kri 'blood', dětь 'children'). There are also many lexical archaisms, such as bali 'physician', potь pěga 'adulteress', rěsnota 'truth' etc. Some morphological and syntactic inovations in Croatian Church Slavonic are also interesting for the typology of the Slavic languages, e.g. aorists in -ota, bisi (3rd P. sg. aor. of biti), nominative absolute, periphrastic negated imperatives with the verb nebrěĉ i etc.