Representatives of the classes Arachnida and Crustacea occur throughout the world and are a substantial and essential component of different ecosystems. There are published records from Ukraine of 2594 species of the Arachnida (known total worldwide, 52000 species) and 811 species of Crustacea (known total worldwide, 80000 species). In spite of their immense ecological and practical importance, research into this group in Ukraine is now slowing down dramatically because of insufficient funding, and some groups (e.g. Pseudoscorpiones) remain almost unstudied, or insufficiently known (Opiliones, Acari, Aranei). Very urgent priorities are the conservation of existing collections, the creation of a computerized database of the distribution of the country's known species (dealing first of all with those which are extinct), and the protection of rare and endemic species (out of more than 2500 known arachnid species, only 2 are currently included in Ukraine's Red Data Book, whereas among spiders alone there are not less than 10 endemic species). To deal with these priorities, it will probably be necessary to seek non-core budget funding.