Fifteen patients, all women, reacted to palladium chloride patch test at 1% in pet, showing a clear allergic reaction at 48 and 96 hours. All of them showed patch test positive to nickel sulphate, 5% in pet at the same time. These nickel reactions were relevant. It was not possible to establish the clinical relevance of the palladium responses. In vitro test was performed in four patients and nine controls, with four palladium chloride solutions (50 μmol/L, 40 μmol/L, 25 μmol/L, and 5 μmol/L) and 40 μmol/L nickel sulphate solution. In all of the patients tested, a good correlation was obtained with “in vivo” and “in vitro” test with nickel solutions. In vitro test with palladium did not confirm the patch test results. Atomic absorbimetric technique was used to search traces of impurities of nickel in the syringe containing palladium chloride for testing, with negative results in the samples studied.