Vilainiai (formerly Russian: Вилайни, Polish: Wiłajnie) is a village in Kėdainiai district municipality, in Kaunas County, in central Lithuania. According to the 2021 census, the village had a population of 1157 people. It is located next to the north eastern edge of Kėdainiai, on the left bank of the Nevėžis river. There is a kindergarten, a library, a sports school, a culture house, Water Management Institute of Vytautas Magnus University Agriculture Academy.

Vilainiai has been known since 1744. There was a manor and a watermill till the mid-20th century. It developed largely during the Soviet era as a settlement of Land Improvement Institute.

Historical population

Year Pop. ±% p.a. 1859 25 —     1902 79 +2.71% 1923 132 +2.47% 1959 239 +1.66% 1970 565 +8.14% 1979 1,414 +10.73%	Year Pop. ±% p.a. 1987 1,691 +2.26% 1989 1,895 +5.86% 2001 1,490 −1.98% 2011 1,330 −1.13% 2021 1,157 −1.38%
Source: 1902, 1923, 1959 & 1970, 1979, 1989, 2001, 2011, 2021

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  Vilainiai roadsign
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  Wayside cross
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  Water towers in Vilainiai
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  Eldership administration