The aim of conducting this research issurveying the genetic diversity
of cultivars and lines of tetraploid cotton by the use of quantitative morphologic properties of fibers. To this aim, 8 lines along with 2 observed cultivars (Sahel and Varamin) were evaluated during agricultural year 2012 in the form of randomized complete block design (RCBD) with three repetitions in Hashemabad research station of Gorgan. The variance analysis of different properties showed that plant height, earliness, overall yield and quality index were significant which indicated the genetic diversity
among cultivars and lines. According to the path analysis the highest correlation on total yield was related to earliness (P= 0.399) and it is possible to choose this trait as the criterion. Surveying the correlation coefficients of studied properties showed that overall yield had the highest positive and significant correlation with earliness at probability level 1%; also the highest and lowest phenotypic coefficients belonged to properties of earliness with 23.87% and fibers weight with 3.42%.