Extracts of Acacia longifolia yielded two major histamine aldaloiks which were separated by tlc. Nmr, ms, uv, ir and other physical measurements led to structural assignments of the compounds as N-(2-imidazol-4-yl-ethyl)-trans-cinnamamide and N-(2-imidazol-4-yl-ethyl)-deca-trans-2, cis-4-dienamide.