Data communication systems are often beset with the problem of dc offset. The questions addressed and answered in this concise paper are: 1) can minimum mean-squared error (MMSE) equalizers correct dc offset? 2) what are the exact effects of the equalizer on offset, and offset on residual MSE? We conclude that MMSE equalizers can reduce the effects of dc offset but cannot completely eliminate them. Quantitative results give residual MSE as a function of offset magintude, equalizer length, and signal energy.