In the letter a new adaptive procedure for the detection of a radar target in clutter is described. The procedure is based on the development of linear models for the two hypotheses H0 and H1. Under hypothesis H0, there is no target present, and the received signal is modelled as a regressive process. Under hypothesis H1, a target is present and the received signal is modelled as an autoregressive process. Results based on actual radar data are included to confirm the validity of this new approach, and comparison is made with the previously published innovations-based detection algorithm.