eett6f is a computer program for calculating cross sections of processes of the electron-positron annihilation into 6 fermions relevant for a top-antitop-pair production and decay at centre of mass energies typical for linear colliders. The program has been written in Fortran 90 . Version 1.0 of the program allows for calculating both the total and differential cross sections at tree level of the Standard Model. The program can be used as the Monte Carlo generator of unweighted events as well.