The 4 pi beta(LS)-gamma coincidence counting system of KRISS (Korea Research Institute of Standards and Science) has been operated in the analog signal-processing mode. We develop and implement a digital sampling method using a commercially available analog to digital converter. In the implementation, we digitize the amplified pulse trains generated from three detector channels and determine the locations and amplitudes of peaks using a peak detection algorithm. We develop offline analysis routines to process the recorded locations and amplitudes for activity determinations by means of the efficiency-extrapolation method. In the activity determinations we can make corrections for the effects of out-of-channel events and correlation between data points. We validate the digital sampling method by measuring Co-60 activity and comparing the measurement results with those obtained in the analog mode. The digital method is capable of facilitating the activity standardization of radionuclides with very short half-lives. (C) 2010 Elsevier B.V. All rights reserved.