Flax (Linum usitatissimum L.) is one of the oldest domesticated plants — it was cultivated as early as in ancient Egypt and Samaria 10,000 years ago to serve as a source of fiber and oil, whence it later spread around the world. Compared with other plants, the flax genome consists of a high number of repetitive sequences, middle repetitive sequences and small repetitive sequences of nucleotides. The aim of the study was to analyze the stability of the existing trinucleotides motifs of microsatellite DNA of the flax genome (genotype Kyivskyi), growing in the Chernobyl conditions. The Chernobyl area is the most extensive “natural” laboratory suitable for the study of radiation effects. Over the last 20 years, the researches collected important knowledge about the effects of low and high radiation doses on the DNA isolated from the plant material growing on the remediated fields near Chernobyl and the plant material from fields contaminated by radioactive cesium 137Cs and strontium 90Sr. Using eight pairs of microsatellite primers, we successfully amplified the samples from the remediated fields. For each primer in the control samples and remediated samples, we detected 1 to 3 fragments per locus, each in size up to 120 to 250 base pairs. The applied microsatellite primers confirmed the monomorphic condition of microsatellite loci.