The spermatologic characteristics of European flounder (Platichthys flesus luscus) were determined. Flounder were collected during the spawning season and sperm of eight males was extracted by abdominal massage. Body weight and total length of the flounder were measured, volume, motility, duration of motility, spermatocrit, density, and pH of the sperm were determined, and correlations between the spermatologic characteristics and weight and length were investigated. Mean values were 0.7 +/- 0.16 ml for sperm volume, 87.5 +/- 3.66% for motility, 22.0 +/- 1.49 min for duration of motility, 94.0 +/- 1.22% for spermatocrit, 2.7 +/- 0.16 x 109/ml for density, and 6.9 +/- 0.05 for pH. Body length and sperm volume had positive correlations with body weight (p<0.01), but the correlation between length and sperm volume was negative (p<0.01). Likewise, the correlations between spermatocrit and total length, sperm volume, and density were negative (p<0.05).