The performance of two respirable aerosol samplers was tested to determine performance specifications. Factors taken into consideration included sampling efficiency, bias, sampling method imprecision, intersampler variability, pump flowrate inaccuracy, filter weighing error, and accuracy. The two respirable aerosol samplers chosen for evaluation were the Higgins and Dewell (HD) sampler and the 10 millimeter nylon Dorr Oliver cyclone. Four tests were repeated at four different flowrates on each of eight samplers. Aerosol, upstream to the sampler, was introduced in a low speed wind tunnel. Procedures were used to ensure homogeneity of the aerosol in the areas being tested by the samplers. The test aerosol selected was potassium-sodium-tartrate (304596). Mass median diameter of the particles was 4 micrometers, with a standard deviation of 2.2. Upper limits on sampler inaccuracy were determined. The authors recommend that the HD sampler be operated at 2.2 liters per minute and that the nylon cyclone be operated at 1.7 liters per minute. These recommendations closely match the international sampler standard adopted by international organizations. The authors suggest that adoption of performance standards could result in improvements in sampler design, including the introduction of samplers with added capabilities.