A cytogenetic study was performed on M4 generation of gamma irradiated lines of Shirpan cultivar of tetraploid cotton (Gossypium hirsutum L.). A significant difference was observed in cytogenetical characteristics such as the number and type of quadrivalents as well as percentage of cells showing abnormality among the irradiated and non irradiated lines. Cytomixis and post- pachytene diffuse stage was observed in the gamma irradiated lines, but not in the control line. There was an indication that the lines with good agronomic characters possess meiosis with a low abnormality and a higher value of alternate quadrivalents.