Registration of Microbial Pest Control Agents (MPCAs) under Subsection M of the EPA Pesticide Assessment Guidelines requires that the susceptibility of nontarget species be tested. Honey bees as supplemental pollinators of many entomophilous crop species and as producers of honey and wax, are considered a premier beneficial species on a cosmopolitan scale. The document outlines proposed methods of testing the susceptibility of honey bees to MPCAs. These methods will have to be adapted to specific microbial agents, depending upon the known mode of action, proposed stadium of the nontarget species (adult or immature stages) and the potential mode of environmental encounter. Precise correlations in dosage relationships between laboratory and field pathogenicity would be rare. Therefore, interpretation of test results in predicting the effects of the MPCAs under field conditions requires caution. The ultimate evaluation of honey bee susceptibility to MPCAs depends on the effect on colony health and productivity.