This paper presents an adaptive error concealment technique for MPEG (Moving Picture Experts Group) compressed video. Error concealment algorithms are essential for many practical video transmission scenarios characterized by occasional data loss due to thermal noise, channel impairments, network congestion, etc.. Such scenarios of current importance include terrestrial (simulcast) HDTV, teleconferencing via packet networks, TV/HDTV over fiber-optic ATM (asynchronous transfer mode) systems, etc. In view of the increasing importance of MPEG video for many of these applications, a number of error concealment approaches for MPEG have been developed, and are currently being evaluated in terms of their complexity vs. performance trade-offs. Here, we report the results of recent work on a specific adaptive algorithm that provides excellent robustness properties for MPEG-1 video transmitted on either one- or two-tier transmission media. Receiver error concealment is intended to ameliorate the impact of lost video data by exploiting available redundancy in the decoded picture. The concealment process must be supported by an appropriate transport format which helps to identify the image pixel regions which correspond to lost video data. Once the image region (i.e., macroblocks, slices, etc.) to be concealed are identified, a combination of temporal and spatial replacement techniques may be applied to fill in the lost picture elements. The specific details of the concealment procedure will depend upon the compression algorithm being used, and on the level of algorithmic complexity permissible within the decoder. Simulation results obtained from a detailed end-to-end model that incorporates MPEG compression/decompression and a custom cell-relay (ATM type) transport format are reported briefly.