The meaning of the term “green city” today is more related to sustainability rather than to vegetation or greenery. Therefore, the aim of this research is not to develop another complex green index, but simply to calculate and compare a share of greenery among functional urban areas of three Baltic capitals. Comparison was done using GIS tools and analysing Urban Atlas, CORINE and degree of soil sealing datasets. Although the results of Urban Atlas and CORINE datasets showed slight disagreement, it has been discovered that Tallinn has the highest share of greenery, Vilnius is in the middle and Riga is the last. Analysis of 1990, 2000, 2006 and 2012 CORINE datasets showed the highest relative decrease of greenery in Riga (2.53 %) over time, Tallinn was the second (1.44 %) and the smallest decrease (0.53 %) was in Vilnius. The analysis of degree of soil sealing demonstrated the highest relative share of pervious surfaces in Tallinn (95.5 %) and the smallest share in Vilnius (92.1 %), therefore this research nominates Tallinn as the greenest (literally) capital of the Baltic States.