The present article represents the first part of a review of fossil heterostigmatic mites collected from late Eocene Rovno amber. Here, mites of the families Tarsocheylidae, Dolichocybidae, and Acarophenacidae are described, with Tarsocheylidae and Dolichocybidae recorded for the first time from amber. A new genus and four new species are described, namely, Hoplocheylus similis sp. nov. (Tarsocheylidae), Dolichocybe elongata sp. nov. (Dolichocybidae), Proadactylidium fossibilis gen. and sp. nov. and Paradactylidium sineunguis sp. nov. (Acarophenacidae). The extant species Acarophenax lacunatus Cross and Krantz, 1964 and A. assanovi Livshitz and Mitrofanov, 1974 are transferred to the new genus Proadactylidium. A revised key to the genera of Acarophenacidae is presented. The homologies of prodorsal setae in Acarophenacidae are reconsidered and reviewed.