Ultrafast laser pulses transmitted through excised human breast tissue have been detected by a streak camera. Experimental data of the temporal spread of the ultrafast pulse during the transmission through the tissue have been analyzed using the Laguerre expansion technique. This method treats the medium of propagation as a “black box system” and using data sets of incident–transmitted pulse, it relates to this system a set of coefficients as well the first-order system kernels. This analysis could present an alternative method of tissue characterization when, due to the limited optical thickness of small biopsy samples, the photon diffusion approximation cannot be used successfully. © 1999 American Institute of Physics.