Six varieties of watermelon (Sugar baby, Sugar dragon, Kaolack, Crimson sweet, Koloss and baby doll) were evaluated in the field to assess the genetic parameters associated with morphological traits in the watermelon genotypes. The experiment was laid out in Randomized Complete Block Design (RCBD) in three replications. There were variations in number of branches per plant, vine length, number of days to 50% flowering, number of male flowers, number of fruits per plant and fruit weight per plant. Low response to selection and genetic variation was observed in most traits. The number of days to 50% flowering had the highest heritability estimates (97%), genetic gain of 15.84% and genetic advance of 5.33. Fruit weight per plant had high heritability estimates of 89%, moderate genetic gain of 46.20% and genetic advance of 2.31. Moderate broad sense heritability estimates ranging from 55% for number of male flowers per plant to 63% for number of fruits per plant. Mean branch number had the highest genetic gain of 49.33% but moderate heritability estimates of 58.91% signifying moderate response of selection. Koloss and Kaolack had the highest genetic performance for fruits yield than Baby doll and other varieties plant in the humid environment. Therefore, Koloss and Kaolack is recommended in the humid ecology and should be cultivated in the ecological zone.