Résumé : A brief introductory survey of γ-ray detector arrays and in-beam electron spectrometers developed during the last three lustra is followed by a broad discussion of the general requirements for single and multiple in-beam e-γ spectrometers. A detailed analysis is made of a few important tools for reducing the low-energy electron background (i.e. simultaneous E-Bp selection, true and random coincidence rates, EM static fields around the target region). This survey and discussion are illustrated by the results of several in-beam e-γ measurements dealing with nuclear spectroscopic investigations of a few medium and heavy nuclei. © 1999 Elsevier Science B.V. All rights reserved.