The crystal structure of the title compound has been determined in order to study the structure-reactivity relationship of a bicyclo compound. C15H15O3, M 257.29, monoclinic, space group P21/a, a = 24.122(6), b = 6.990(2), c = 7.800(2) Å, β = 94.27(2)°, V = 1311.5(6) Å3, Z = 4, Dx = 1.304 g cm−3, μ = 7.56 cm−1 for Kα. The final R-value is 0.062 for 1948 reflections. The molecular structure is essentially the same as that of the N-benzoyl derivative of the bicyclo compound. An elongation of the C–N bond distance in the lactam-amide moiety, which had been found in the N-benzoyl derivative, was observed and compared with that in the unmodified bicyclo compound. There seems to be little extension of the conjugation of the olefinic group to the carbonyl or phenyl groups in a cinnamoyl moiety, according to the C=C and Csp2–Csp2 distances.