Some population parameters of native trout (Salmo trutta L.) in Ayg›r Lake were examined in this research. For this purpose, total 40 fish caught between June and August 1996. The population was composed 22.5% females and 77.5% males and the differences between sexes were statistically significant (p <0,05). The weighted average of fork lengths and body weights were 17.42cm and 70.36g, respectively. The equation of length-weight relationship calculated from all fish was found as W=0,009035x FL3,074. Condition factor (K) was also found as 1,13.