If you wish to visit Lithuania for a short period of time, you must obtain a visa prior to entry if you come from a country with a visa requirement for entering Lithuania. Ukrainian nationals require a visa to Lithuania.
A Schengen visa is an authorisation for a foreign national to visit Lithuania and/or the other Schengen countries* for a limited period of time (90 days during any 180 days period). If you wish to reside in Lithuania for an extended period of time (more than 90 days during any 180 days period), you need to apply for a long term visa (National visa, type “D”).
The possession of a visa does not confirm an automatic right of entry to a Schengen country. The visa holder is requested to fulfill the entry conditions at the border (valid travel document, valid visa, justified purpose of travel, sufficient means of subsistence, etc.)
*Schengen countries: Austria, Belgium, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Italy, Latvia, Lithuania, Liechtenstein, Luxembourg, Malta, The Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden and Switzerland.