Intradermal tests are widely used to support the diagnosis of dermatological and nondermatological diseases. They are mainly indicated for the detection of immediate (Type I hypersensitivity) and delayed type hypersensitivity (DTH, Type IV hypersensitivity) towards exogenous or endogenous antigens. Intradermal tests for the diagnosis of infectious and non-infectious diseases in relevance to dermatology are discussed in this review.