The summarized results of 25-year studies of department of human genomics of IMBG NASU are presented. The investigations were focused on identification of molecular genetic nature of human genome coding and non-coding region mutations (genetic polymorphisms) and rearrangements, their spectrum, and origin in Ukrainian population. The role of genome heterogeneity in some severe monogenic and complex disorder pathogenesis has been shown. The data concerning correlation between certain determinator gene mutations and phenotypical manifestation of most common in Ukraine monogenic diseases have been demonstrated. Moreover, the role of modifying genes in specific clinical phenotype variations has been shown. Origin of particular mutant alleles and main mechanisms of their frequency maintenance in Ukrainian population have been investigated. The data about association of some polymorphic variants with infertility, cardiovascular diseases (ischemic stroke) as well as mass infectious diseases (hepatitis C, AIDS) outcome and standard therapy efficiency have been presented. The first results and prospects for candidate genes of neurodegenerative disorders and intellectual disability search using whole genome CNVs screening are shown.