A sample (N = 16,204) of the U.S. population, 6 to 74 years of age, was examined in NHANES II with a variety of routine medical procedures, including prick-puncture allergen skin testing (AST), venipuncture, and body measurements. Eight unstandardized extracts licensed by the Food and Drug Administration, a positive and negative control, were used. AST was performed to screen the population for immediate hypersensitivity responses to common aeroallergens. No anaphylactic reactions after AST were observed. One asthmatic reaction occurred during venipuncture. Other adverse reactions (ARs) were limited to syncope, near syncope, and malaise. The rates for any AR were venipuncture, 0.49% (95% confidence interval [CI], 0.38% to 0.60%); AST, 0.04% (95% CI, 0.01%-0.08%); body measures, 0.006% (95% CI, 0 to 0.018%). Sex or fasting status had little effect on the occurrence of AR. The age group 20 to 49 years had the highest occurrence of any AR to venipuncture (0.87%; 95% CI, 0.633% to 1.107%). The risk of prick-puncture AST with eight extracts licensed by the Food and Drug Administration is low and similar to other routine medical procedures.