Sex ratio, age and growth, length and age at sexual maturity, and spawning season of the Mediterranean needlefish Tylosurus acus imperialis (Rafinesque, 1810) off Tunisian coast were investigated. A total of 126 individuals (54 females and 72 males) were sampled. The length weight relationships for females and males were W = 0.0027 L2.832 (s.e.a ± 0.004; s.e.b ± 0.238) and W = 0.0026 L2.827 (s.e.a ± 0.002; s.e.b ± 0.188), respectively. Otolith reading revealed that females belonged to age groups from 0 to 6 years and males from 2 to 4 years. Most of individuals were of age groups 3. The parameters of the von Bertalanffy growth function were L∞=123.78 cm (s.e. ± 17.93), k = 0.2 year-1 (s.e. ± 0.07) and to = -2.28 year (s.e. ± 0.57) for females and L∞ = 92.28 cm (s.e. ± 5.93), k = 0.5 year-1 (s.e. ± 0.15) and to = -1.16 year (s.e. ± 0.45) for males. First sexual maturity was estimated at total length of 79.09 ± 0.71 cm for females and 79.18 ± 1.83 cm for males. Gonadosomatic index pattern indicated the spawning season extended from May to July.