<jats:title>Abstract</jats:title><jats:p>From the root bark of <jats:italic>Capparis decidua</jats:italic> (Capparidaceae), a new spermidine alkaloid, capparisinine was isolated. The structure <jats:bold>1</jats:bold> of the alkaloid was determined by means of spectral studies and correlation with other known alkaloids of similar structures. Capparisinine is a positional isomer of capparidisine which is known already as a constituent of this plant.