Abstract Background: A connection between patch test reactions to paper extracts and contact allergy to rosin (colophony) has been demonstrated. Objective: We wanted to determine whether a difference in the allergenic activity of various types of paper is related to a difference in the pulp. Methods: Patients with dermatitis who were frequently exposed to paper were patch tested with extracts from various papers and the standard series. The extracts were also tested in volunteers with or without contact allergy to rosin and in animals. The rosin compounds in the papers were analyzed by gas chromatography. Results: The subjects reacting to paper extracts also reacted to rosin. Most reactions were found to the papers produced from mechanical pulps, which contained the highest analyzed amounts of rosin compounds. Animals sensitized to rosin reacted only to paper from mechanical pulp. Conclusion: Papers based on mechanical pulps that are considered to be environmentally friendly have a greater potential to elicit positive patch test reactions than papers made from other pulps. The increased use of mechanical pulps in different applications may increase the incidence of rosin-related hand eczema.