Mąstautai (formerly Russian: Мостовты, Polish: Mostowty) is a village in Kėdainiai district municipality, in Kaunas County, in central Lithuania. According to the 2011 census, the village had a population of 9 people. It is located 2 kilometres (1.2 mi) from Pajieslys village, in the Pajieslys Geomorphological Sanctuary.

At the beginning of the 20th century Mąstautai was an okolica, a property of the Kučiauskai, Mackevičiai and Šimkevičiai families.

Historical population

Year Pop. ±% p.a. 1902 49 —     1923 23 −3.54% 1959 25 +0.23% 1970 24 −0.37%	Year Pop. ±% p.a. 1979 11 −8.30% 1989 8 −3.13% 2001 15 +5.38% 2011 9 −4.98%
Source: 1902, 1923, 1959 & 1970, 1979, 1989, 2001, 2011