Seven methods for the evaluation of the seismic quality factor Q have been investigated: (1) wavelet modelling, (2) spectral modelling, (3) spectral ratio method, (4) matching technique, (5) amplitude decay method, (6) risetime method, and (7) the determination of Q using the analytical signal. These methods were tested using three theoretical VSP seismograms which are based on the same velocity and Q depth model. Whereas in the noise-free case the method of the analytical signal (7) proved to be superior to all other methods, the modelling techniques (1) and (2) seem to have advantages when minor noise is present. In the case of intensive noise it is hard to obtain any reliable estimate of attenuation.