The chromosomal techniques in agriculture, especially in breeding studies, are progressing in parallel with developments in the field of cytogenetics in biology. These techniques are used in crop improvement studies (e.g., more resistant, more productive, more nutritionally valuable etc.) using genetic information from plant genomes, particularly in economically important plants. In short, the chromosomal techniques are important in obtaining agricultural products with desirable improved traits. The areas using chromosomal techniques in agriculture and their detailed examination will form the basis of this section. These can be listed as cytogenetics, hybridization and polyploidy, chromosome engineering, chromosome-specific breeding programs, functional genomics, genetic mapping, genome sequencing, polymerase chain reaction (PCR), clustered regularly interspaced short palindromic repeats (CRISPR-CAS9) technology, and marker-assisted selection (MAS). The classical cytogenetic methods are the oldest strategies used in agricultural crop improvement. The hybridization, polyploidy, chromosome engineering, and chromosome-specific breeding programs are the continuation of these strategies, the molecular cytogenetics represents the cutting edge. In the present chapter, application models of chromosomal techniques in agriculture are evaluated from the oldest to the newest. The first of these, cytogenetics, is a sub-branch of genetics that deals with the number, shape and structure of chromosomes. The hybridization is a process in which two complementary single-stranded molecules combine to form a double-stranded, while polyploidy is the presence of more than two sets of chromosomes in somatic cells. The chromosome-specific breeding programs are artificial selection methods used to obtain agricultural products with desired traits. The molecular cytogenetics is a more advanced model of classical cytogenetic methods combining molecular biology and cytogenetics techniques