During the 1996–2004 period 850 patients, who were participants in diminishing the consequences of the Chernobyl nuclear accident (PDCCNA), and their children, were investigated in terms of clinical, immunological and cytogenetic analyses. The clinical investigations indicate that the PDCCNA patients, when compared with patients of a control group, were more susceptible to infectious and non-infectious diseases, with the prevalence of large polymorphism of nervous, heart-vascular and gastric-intestinal system, which were accompanied by circulatory disorder of the vegetative nervous system. The immunological analysis revealed alterations in the immune system of the PDCCNA. Cytogenetic research of the lymphocyte cultures of peripheral blood of PDCCNA members living in the Republic of Moldova in the last 15–20 years after the accident, and their children, revealed the deterioration of the hereditary system, being expressed through a high level of genomic, chromosomal, and chromatid type aberration. Chromosomal type of aberrations prevailed in the adults and chromatid type in the children.