4 strips of 5 Epquick™ patch tests (9 allergens plus (control) were applied symmetrically in duplicate on the left and right sides of the upper back in SOU consecutive patients 70 positive allergic patch test reactions were recorded on the left side and 67 on the right side. 67 positive reactions were concordat on both sides (64 with the same score of intensity and .1 with a different score). 3 positive reactions (in 2 patients) on the left side were negative on the right side (1 TMTD. I cobalt chloride and t wool alcohols). At rechallenge 6 weeks later, they were positive. No explanation could be found for negative results at the first challenge on one side and not on the other. The rate of non‐reproducible positive results to the overall number of positive reactions was 4.2%. The good reproducibitiy rate (95.8%) provides useful information for furl her comparative stud