ABSTRACT Background Contact allergy to benzisothiazolinone (BIT) has increased in recent years, but exposure to it is not always found. It's important to know whether the gloves might be an isothiazolinone source especially in patients with symptoms from gloves and isothiazolinone contact allergy with or without allergy to rubber chemicals. Objectives To present results of chemical analysis of isothiazolinones in disposable rubber gloves of patients in an occupational dermatology clinic. Methods We went through our chemical analysis record from 2018–2025 and identified isothiazolinone analyses done from disposable rubber gloves. The chemical analysis of glove extracts was done by liquid chromatography‐mass spectrometry (LC–MS). We screened the respective patients' files and collected information on their occupation, glove usage, patch test reactions as well as basic information on their hand eczema. Results We discovered BIT in 30/54 (60%) analysed gloves (27 nitrile rubber gloves, 2 neoprene rubber gloves and 1 natural rubber glove) in concentrations of 0.3–73.7 ppm (mean 12.7 ppm, median 4.2 ppm). Methylisothiazolinone (MI) was found in solitary gloves in small concentrations. Isothiazolinone‐containing gloves were samples from altogether 21 patients, and six of them had several gloves that contained isothiazolinones. Many patients had also other isothiazolinone sources at work or at home. Conclusions Disposable rubber gloves are a possible BIT source. Several gloves contained BIT in a concentration that may be enough to induce contact allergy when gloves are used frequently.