Twenty volunteers were skin tested with seven concentrations of histamine phosphate and a glycerosaline control to determine the relative sensitivity and precision of four skin test devices: Greer Pen (GP), Greer DermaPIK (DP), Center Multi-Test (MT), and Morrow Brown needle (MB). The end points of the study were (1) wheal and flare response of each device, with a dose-response curve, (2) the time required to apply each set of eight tests, and (3) the volunteers' subjective assessment of each device. On a different day, 10 of the volunteers were tested to determine the precision of each device. Dose-response curves for half-log dilutions of histamine phosphate were produced with a glycerosaline control. The DP and GP induced wheal and flare responses discernible from that of the glycerosaline control at a lower concentration of histamine phosphate than the MB and MT. The DP took a shorter time to apply eight samples than any other device. The MB was preferred by the most volunteers, but any device tested on the upper half of the back was usually preferred over that tested on the lower half. When 5 mg/ml histamine phosphate was used, coefficients of variation for each device demonstrated that for wheals the precision of the DP, GP, and MT was similar (mean, 21.1%, 23.1%, and 24.5%, respectively). The MB was larger (mean, 59.9%). For flares, the precision of GP and DP was similar (mean, 22.0% and 23.5%, respectively), with the MT and MB larger (mean, 35.5% and 58.2%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)