Investigation of excitonic lines in differential surface photovoltage (DSPV) spectra of p-type (Be) 5-doped GaAs/AlAs multiple quantum well (MQW) structures is reported. From the lineshape analysis of the DSPV spectra, the energies and line broadening parameters for a large number of QW related excitonic transitions were determined. It is found that transition energies are in a good agreement with calculations carried out within the envelope function approximation taking into account the nonparabolicity of energy bands. Examining the dependence of the exciton linewidth on the QW thickness, the line-broadening mechanisms were revealed and interface roughness in the MQW structures was evaluated. An asymmetrical lineshape of certain excitonic transitions in SPV spectra of MQW structures was shown to be related to the Fano resonance.