Sensitization by para-tertiary-butylphenolformaldehyde resin (PTBP-FR), which is particularly useful as a leather glue, has been known for 30 years. We retrospectively studied the clinical aspects of those patients with a PTBP-FR allergy among 1966 patients in whom contact dermatitis was confirmed by patch testing. A positive patch test to PTBP-FR was present in 30 patients (1.5%), 24 of whom were women. Exposure to PTBP-FR as a cause of the dermatitis was "certain" in 7, "very likely" in 6 and "unclear" in 17. 67.7% of the patients had a multiple allergy. In 43.3% of the patients, a history of atopy was found. No clear association of PTBP-FR sensitization with allergies to phenolformaldehyde resin (P-FR) or free para-tertiary-butylphenol (PTBP) emerged in this group of 30 patients. This study supports the hypothesis that PTBP-FR and P-FR do not contain the same sensitizers. Follow-up of 26 of the 30 patients showed a favourable course, dependent on identification of the source of exposure, avoidance of further contact and absence of sensitization to multiple allergens.