Guinea pigs were sensitized with lysozyme-carrageenan mixture, BSA-carrageenan mixture, or BSA-carrageenan complex coupled covalently with BrCN. The control animals were sensitized with the antigen alone or with Freund’s adjuvant. The animals were skin-tested with the antigens 2–6 weeks later. Carrageenan was found to have a potent adjuvant activity – especially in delayed hypersensitivity.