Busereline acetate is an LH-RH agonist that was found to induce local reactions at the injection site or generalized minor skin reactions in some patients. Since these reactions may represent the first reaction of systemic anaphylaxis, we tested the non-specific histamine releasing activity of this drug by intradermal skin tests. It was found that all subjects tested had a positive wheal and flare reaction, the flare being significantly decreased by terfenadine. Benzyl alcohol, the preservative used in commercial preparation of busereline acetate, did not elicit a positive wheal and flare reaction in two patients who had experienced a clinically noticeable reaction. It is concluded that busereline is likely to be a non-specific histamine releasing compound.