topical use of penicillin and most rarely after oral administration The incidence of such reactions has been estimated to vary from 1% to 8% in the general population. Skin tests for the determination of penicillin allergy are unreliable and dangerous when penicillin g itself is injected n small quantities intracutaneously. On the other hand preparations are available, at least for experimental purposes, in which penicilloylpolylysine(PPL) is suitable for testing allergy to the major determinant. Also, a mixture of penicillin, penicillate, and other products is suitable for testing allergy to the minor determinants. Despite these refinements in diagnosing penicillin allergy, tests are mot completely reliable. As a consequence, the history of previous reactions is very important, and even in the presence of a negative intradermal test, it is best to be prepared for the possibility of anaphylactic reaction whenever the antibiotic is injected In addition to hypersensitivity reactions, penicillin is capable of producing other adverse effects. Neural tissue may be susceptible to penicillin, particularly when vulsive phenomena have been noted following such procedures. There is seldom any reason for injecting penicillintopical use of penicillin and most rarely after oral administration. The incidence of such reactions has been estimated to vary from 1% to 8% in the general population. Skin tests for the determination of penicillin allergy are unreliable and dangerous when penicillin G itself is injected in small quantities intracutaneously. On the other hand, preparations are available, at least for experimental purposes, in which penicilloylpolylysine (PPL) is suitable for testing allergy to the major determinant. Also, a mixture of penicillin, penicilloate, and other products is suitable for testing allergy to the minor determinants. Despite these refinements in diagnosing penicillin allergy, tests are mot completely reliable. As a consequence, the history of previous reactions is very important, and even in the presence of a negative intradermal test, it is best to be prepared for the possibility of anaphylactic reaction whenever the antibiotic is injected. In addition to hypersensitivity reactions, penicillin is capable of producing other adverse effects. Neural tissue may be susceptible to penicillin, particularly when vulsive phenomena have been noted following such procedures. There is seldom any reason for injecting penicillin