This study aims to establish the relationship of length-weight and evaluate the condition of the condition of fish Tor (Tor soro) in the waters of Asahan River, North Sumatra. Sampling was carried out once a month from February to May 2019. A total of 756 fish were caught using 1.5 - 3 inch mesh-gill nets. The total length and weight of sample fish ranges from 120 - 250 mm and 64 - 161 grams, respectively. The relationship of length-weight is W = 3.000x10⁵ 2.72 Log L. These results indicate that the long-weight relationship has a high correlation (R²> 0.978). The conductive factor varies from 0.977 to 1,070. Females have better conditions than male fish.