Hypersensitivity to beta lactams, especially that mediated by IgE or IgG4, is the most frequent complaint of adverse drug reactions. There are multiple studies dedicated at establishing a method that can permit us to arrive at an accurate diagnosis, but from these studies one deduces that the difficulty lies in the lack of a test with a 100% reliability. In the present study we evaluate the correlation between the different methods. For this we selected 16 children, composed of 8 males and 8 females, whose ages ranged between 2 years 7 months and 9 years 8 months, and who had a reaction to penicillin G via parenteral. The following tests were done on them: Skin tests with a major determinant antigen (constant composition and molecular weight), with minor determinants. Human basophil degranulation test (modified Leynadier technique). Mathov's progressive controlled provocation test, which we considered the most reliable. Only in eight cases a diagnosis of penicillin allergy was arrived at. The correlation between the different tests were: Mathov - HBDT 93.75%; Mathov - PPL 93.75% and PPL - HBDT 87.5%.