N‐Isopropyl‐N′‐phenyl‐p‐phenylenediamine is used mainly as a stabilizer (antioxidant) in the rubber industry. The main field of application is the tyre manufacturing sector. In addition, antiozonization agents such as N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine are found also in other rubber products. N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine is non irritating to the skin. The skin‐sensitizing effects of N‐isopropyl‐N′‐phenyl‐p‐phenylenediamine are sufficiently documented, both as a result of clinical observations in humans and the findings in animal studies. N‐Isopropyl‐N′‐phenyl‐p‐phenylenediamine is therefore given the designation “Sh” (for substances which cause sensitization of the skin). As there are no data available for sensitizing effects on the airways, the substance is not designated with “Sa”.