Abstract: The age, growth and reproductive properties of sand smelt, Atherina boyeri Risso 1810, caught from Lake Iznik (Northwest Turkey) were studied by sampling carried out between March 2000 and February 2001. A total of 922 specimens were examined. The age of this species varied from 0-IV and they were composed of 43.6% females, 25.3% males and 31.1% unidentified. The mean total length and weight of the individuals ranged from 12.6-98.2 mm and 0.02-6.89 g, respectively. The Von Bertalanffy Growth Parameters (VBGP) of the population were: L_∞ = 141.11 mm, K = 0.27 year^-1, t_o= -0.49 years for all individuals. Length-weight relationships were estimated as W = 0.002 TL^3.485 for females and W = 0.004 TL^3.062 for males. The sex ratio of males to females was 1:1.7. The spawning period recorded from March to July, with a peak in May. The diameter of ripe eggs ranged from 0.60-1.10 mm. Fecundity was calculated as 450 (1st age group) to 1724 (4th age group) eggs/females.