Background: Allergy is one of the most widespread diseases in this century. Allergy-causing materials used in dentistry are most frequently metals, such as nickel, cobalt, palladium, and amalgam, certain components of dental composites, denture resin materials, and even certain mouthwash components. The aim of this study was to assess dentists’ experience regarding allergies occurring in their practice among patients and among dental team members. Material and methods: We conducted a questionnaire-based study, in which 104 dentists responded. Results: Immediate allergic reactions were more often caused by different drugs, detergents, and anesthetics, while delayed allergic reactions were mostly caused by acrylates. Allergic reactions occurred more often among women than men, but the difference was not statistically significant (p = 0.3). Conclusions: Our results suggest that allergies in dentistry appear mainly among adults, caused mostly by acrylates, metals, and different drugs. Immediate allergic reactions are often present, and mostly women are susceptible to allergies.