The photocleavage of a coumarin derivative dimer is a promising mechanism for laser controlled drug release in medical applications. We studied the efficiency of such reaction after two-photon excitation, comparing femtosecond and nanosecond pulses in the range from 400 to 800 nm. The photocleavage reaction is remarkably more efficient for shorter wavelengths. The spectral profile of the two-photon absorption (TPA) spectrum resembles the single-photon absorption (SPA) spectrum. It was also observed that the photocleavage reaction triggered with femtosecond pulses is about 4.9 x 10(4) times more efficient than the reaction with nanosecond pulses at the same wavelength and beam area. (C) 2007 Elsevier B.V. All rights reserved.