Purpose. Persian walnut (Juglans regia) is one of the most commercially important nut-crop in the world. The nuts of these plants contain a lot of fat, also proteins and carbohydrates. Their nutritional value is significant, as nuts contain a lot of calories and several dietary minerals as well. Walnut cultivation in Latvia used to be fragmentary in past, but these plants are used in breeding work in Latvia as well. Climate changes have created better conditions for growing walnuts, so they can be commercially promising in Latvian conditions as well. Until now, these plants have been little popularized, and their cultivation in Latvian conditions has never been wider explored.

Methods. An initiative by Finnish colleagues in 2021 to obtain walnut genetic material that could be promising for Finnish conditions resulted in amount of impor­tant information obtained in several expeditions. During the expeditions, as far as possible, also by surveying citizens, information was obtained both about some parti­cular walnut trees and about the distribution of walnuts in Latvia. The expeditions were carried out in 2021 and continued in 2022.