Propagation of the zero sound in a superfluid state of 3He is studied theoretically. Limiting ourselves to an anisotropic superfluid state with spin triplet pairing of the type suggested by Anderson and Brinkman, we calculate the attenuation coefficient and the shift in the sound velocity in the superfluid state. The results appear to reproduce at least qualitatively the experimental observation by Lawson et al. and by Paulson et al.