We examine the exclusion limits set by the CDF and D0 experiments on the Standard Model Higgs boson mass from their searches at the Tevatron in the light of large theoretical uncertainties on the signal and background cross sections. We show that whe
n these uncertainties are consistently taken into account, the sensitivity of the experiments becomes significantly lower and the currently excluded mass range $M_H=158$-175 GeV would be entirely reopened. The necessary luminosity required to recover the current sensitivity is found to be a factor of two higher than the present one.
