The energy weighted sum rule of single-particle spectral functions in nuclear matter is studied. The spectral functions include the influence of short-range correlations as generated by the Reid potential in the framework of the self-consistent Greens function method. For the range of momenta studied, the sum rule is rather accurately fulfilled numerically (within 5%). It is observed that the high-energy tail of the particle part of the spectral function exhausts most of the sum rule, which confirms the need for the appearance of single-particle strength at very high energies.