Translation of institutional texts is a challenge for translators due to the importance of conveying the meaning of the context as accurately as possible. The production of a good translation of official documents such as regulations that reflect the institutional register requires consideration of differences in the source and target languages in terms of syntax and lexis. As often as not, this results in transformations in sentence structure and word formation. English word formation, due to different language characteristics differs from Lithuanian in many ways. Although the definition of word formation is quite similar: 'Word-formation' is a traditional label, and one which is useful, but it does not generally cover all possible ways of forming everything that can be called a 'word'." (Bauer, 1983:9). The theoretical part of this paper discusses the main word formation types for the English and the Lithuanian languages. The second, empirical part, deals with the analysis of word formation types in the English language, their transformations in the Lithuanian language and the most common transformation patterns. For the purpose, data from original bilingual documents of the European Union representing the institutional register were collected from EUR-Lex database.