[en] One of the biggest challenges in front of the radiobiologists is to determine appropriate, non-toxic radioprotectors that would prevent the development of radiation-induced injuries. During the last years it was found that natural metabolites could be used as non-toxic radioprotectors. N-acetyl-L-cysteine is an amino acid, which is involved in homocysteine metabolic pathway. Trimethylglycine (betaine) is an amino acid, which is synthesized by choline oxidation. The purpose of that study was to determine the potential radioprotective ability of both amino acids, applied therapeutically separately and in combination to irradiate with 1 Gy absorbed dose human lymphocytes cell cultures. Have been used the dosimetry methods karyotyping of chromosomal abnormalities and cytogenetic assay. Those methods were used to determine the presence of radiation-induced chromosome aberrations, such as dicentric and ring chromosomes. The results of that study showed significant reduction of the examined chromosome aberrations number in the following order: trymethylglicine - N-acetyl-L-cysteine - combined action. Reducing of their number directly correlated with the radioprotective ability of the amino acids to decrease the risk of serious radiation damage