Formulas are derived for the bias in the maximum likelihood estimators (MLE) of the item parameters in the logistic item response model when examinee abilities are known. Numerical results are given for a typical verbal test for college admission. Most typically the bias of an MLE is about one-tenth of its standard error. It is very seldom more than a fifth of its standard error. The effect of bias for individual item-parameter estimates is thus probably negligible. (Author/PN)