The study provides the body mass index (BMI), the prevalence of overweight and obesity in preschool Lithuanian children, 1986-2006. In the 2003-2006 more than 1000 preschool 3-6 year old children from Vilnius (the capital of Lithuania) were investigated according to the standard anthropometric methods. The prevalence of overweight (OW) and obesity (OB) was estimated according to the cut-off points recommended by the International Obesity Task Force (IOTF). Recent data were compared with the data of preschool children from the 1986 Vilnius study and with the data from the other countries. The BMI of preschool children did not change significantly during the last 20 years, except for the statistically significant BMI increment in 6 years old girls. The prevalence of OB among preschool Lithuanian children was low (0.8%-3.7% in boys, and 0-1.9% in girls) and did not change significantly during 1986-2006. The prevalence of OW was higher in preschool girls (10.7%-18.2%) in comparison with preschool boys (6.5%-12.4%). The significant increment of the prevalence of OW was observed among the 6-year-old girls from the 2006 study in comparison with the 1986 study. The possible socio-economic reasons of the defined trend in the BMI and prevalence of OW and OB among preschool Lithuanian children are discussed in the paper.