The application of subband coding to video signals is hindered by the fact that these signals usually have the interlaced format. For proper preservation of the motion in an interlaced video signal, field-based subband coding is preferred. In areas of the video frames without motion, however, frame-based subband coding leads to a lower bit rate than field-based coding. This paper proposes a method to combine the advantages of field-based and frame- based subband coding. The method is called motion-adaptive subband coding. It first divides each video frame into moving and non-moving areas. The moving areas are processed with field-based subband coding, the non-moving ones with frame-based subband coding. Special attention is paid to the transitions between moving and non-moving areas. It is shown that the proposed motion-adaptive subband coding system has a higher performance in terms of bit rate versus picture quality than purely field-based or frame-based subband coding.