Abstract
A study is reported of finite-size, L, corrections for the surface tension of rough interfaces, i.e., for temperatures TR<T<Tc in 3D, 0<T<Tc in 2D. A universal leading contribution proportional to (lnL)L is predicted in 2D. This term is a result of the characteristic rough interface fluctuations. In 3D, the leading corrections are of order 1L.