Genetic diversity is the basis of plant breeding, which is the most important component in the stability of biological systems and ensures the survival of plant populations. Therefore, this research, with the aim of studying the quantitative characteristics of 15 native Iranian melon genotypes using morphological markers in the two crop years of 2016 and 2017, with three repetitions in the form of a complete randomized block design in the city of Mianeh, has been implemented. In the field evaluation, a wide genetic diversity was observed between melon genotypes for morphological traits. The results show that the effect of genotype on the traits of number of days to flowering, average standard petal width, fruit ripening time, peduncle diameter, the ability to keep fruit at room temperature, seed length and fruit length have a significant difference at the probability level of %1 and %5. The percentage of significant indicates the existence of genetic diversity between the melon populations in terms of the investigated traits. The results of composite variance analysis showed a significant difference at the probability level of 1% and 5% between the studied genotypes for the traits of number of days to flowering, days to 50% flowering, petiole length, leaf length, fresh fruit weight, fruit flesh thickness. The number of seeds per fruit, the weight of 100 seeds and the width of the fruit showed the interaction effect of year × genotype. Also, the effect of year was significant for all traits except the average standard petal length, the length of the internodal regions, the length of the peduncle, the diameter of the peduncle, the ability to keep the fruit at room temperature and the seed width at the probability level of %1 and 5%.