1. If you can possibly do so, avoid the use of immunizing agents containing horse serum. It is indeed surprising how many calls allergists receive from physicians and pharmacists asking for confirmation that tetanus toxoid does not contain horse serum. (IT DOES NOT.) Apparently some believe it does. 2. Skin testing for horse serum sensitivity is done only to try to uncover those who may be in danger of experiencing life-threatening 'hypersensitivity reactions. The literature contains reports of anaphylaxis following a skin test dose alone. It might also be necessary to mention that for highly sensitive individuals a test dose of no more than 0.02 ml. of a 1:500 or 1:5,000 dilution should be used for the skin test.2 On rare occasions, equine antitoxins are still, necessary for treatment of venomous snake bites, black widow spider bites, diphtheria, gas gangrene, and botulism, even in the presence of a sensitivity to horses, or of a positive skin test for horse serum.* Cutter Laboratories now has available a rabies immune globulin (human) and it is anticipated that Lederle Laboratories will be licensed to manufacture this product in the near future.' 3. A course of tetanus toxoid should be recommended for persons sensitive to horses or horse serum. Routine booster doses should be given at ten-year intervals. 4. The use of egg-containing vaccines in egg-sensitive patients: (1) Avoid giving unnecessary injections of egg-containing vaccines, such as influenza, to allergics. (2) Avoid the use of vaccines grown on eggs to individuals with a known history of constitutional reactions to egg-containing vaccines. 5. Scratch and endermal tests with vaccines are generally useless. If you do skin tests with the egg-containing vaccines, make serial dilutions of the vaccine with buffered saline. 6. Smallpox vaccination: Smallpox vaccination is not too frequently used any more in this country but is usually safe for almost everyone unless there is active dermatitis in the patient, his or her siblings, or other members of the family. (Eczema vaccinatum is serious, especially if the cornea becomes involved.) The most serious complication of smallpox vaccination, encephalitis, may be indeed an allergic type of response. Also, vaccinia necrosum may occur in persons receiving therapy with immunosuppressive agents including ACTH and cortisone or its derivatives, and some allergic sufferers may be receiving such drugs. Smallpox vaccination is contraindicated for anyone receiving any type of immunosuppressive3 therapy. 7. A strict dosage technique should be employed whenever there is any history of reaction and it is decided to proceed with needed immunization. In this instance, it may become necessary to repeat small doses of serum or of a