The Sluch or Southern Sluch (Ukrainian: Случ, Russian: Случь, Южная Случь, Polish: Słucz, Slovak: Sluč, Jižní Sluč) is a river, a right tributary of the Horyn River, which flows through Ukraine. It has a length of 451 km and a drainage basin of 13,800 km². The Sluch river takes its source in the Ukrainian province of Khmelnytskyi, and then flows through the Zhytomyr and Rivne oblasts, and flows briefly along the Ukrainian-Belarusian border before finally emptying into the Horyn.