The online database of Lithuanian last names is based on the Dictionary of Lithuanian Last Names, with its Volume I issued in 1985, and Volume II in 1989 (managing editor A.Vanagas, authors A.Vanagas, V.Maciejauskienė, M.Razmukaitė). The database presents, alphabetically, nearly all last names of Lithuanian residents with the exception of those that are not embedded in the Lithuanian last names system either functionally or linguistically. Besides, there are some last names of Lithuanian origin that cannot be found in the above Dictionary there, too. Each last name is accompanied by an entry concerning its prevalence and frequency. As many Lithuanian last names had took form and been legitimised before there was a standard language, many of them are presented in the database in their non-standard, dialectal form and possessed of other irregularities comparing to the standard language. Each last name article is followed by comments on the possible origins of the last name: mainly observations from the Dictionary of Lithuanian Last Names, with a few other hypotheses regarding origins added as well.