  The interface tension in the three-dimensional Ising model in the low
temperature phase is investigated by means of the Monte Carlo method. Together
with other physically relevant quantities it is obtained from a calculation of
time-slice correlation functions in a cylindrical geometry. The results at
three different values of the temperature are compared with the predictions
from a semiclassical approximation in the framework of renormalized $\phi^4$
theory in three dimensions, and are in good agreement with them.
