3 minor resin acidS 7 commercial modified‐colophony products of different origins were studied by experimental sensitization by means of a modified FCA method. All 3 resin acids were almost negative. The commercial products gave different results. While the maleic‐modified product of Greek origin showed a strong sensitizing power, the fumaric‐modified, terpene‐phenol‐modified and a disproportioned rosin were only moderate. A remarkable difference was obtained with the Swedish and Finnish tall oil rosins, which, in contrast to the previously studied French product, exhibited only a weak sensitizing capacity. Copyright © 1990, Wiley Blackwell. All rights reserved