Аннотация: Period variation in the system V444 Cyg discovered by Khaliullin (1974) has been confirmed by new observations. It is shown that this variation cannot be due to a presence of a third star in the system. The mass loss by the WN5 star is $\dot{M}=-(1.11\pm0.22)\cdot 10^{-5} M_\odot$/year. The outflow velocity of the matter at the core surface (optical depth $\tau\simeq 1$) is $v_0 = (340\pm160)$~km/s