N-(2-Bromoethyl)-4-piperidino-1,8-naphthalimide, C(19)H(19)BrN(2)O(2), (I), and N-(3-bromopropyl)-4-piperidino-1,8-naphthalimide, C(20)H(21)BrN(2)O(2), (II), are an homologous pair of 1,8-naphthalimide derivatives. The naphthalimide units are planar and each piperidine substituent adopts a chair conformation. This study emphasizes the importance of pi-stacking interactions, often augmented by other contacts, in determining the crystal structures of 1,8-naphthalimide derivatives.