The length, weight and sex distribution of flounder caught by bottom trawl were investigated in relation with seasons in the south-eastern Black Sea (oof Trabzon). The size ranges were 12.0-27.9 cm and 11.2-38.2 cm for male and female flounder, respectively. Mean total length and weight were 27.6±3.61 cm and 248.0±91.25 g for females, 21.1±1.86 cm and 103.4±27.23 g for males, and 24.2±4.30 cm and 172.1±97.88 g for all individuals. Significant differences were found both in length and weight values of flounder between seasons. The length frequen-cies of flounder differed significantly between spring and other seasons (P < 0.001). Significant differences were found for sex ratios of flounder in spring. The length-weight relationship for females, and males were estimated as W = 0.0184 * L2.8485 (r = 0.90), and W = 0.0202 * L2.7898 (r = 0.87), respectively.