The Morris water swimming task provides an ideal way of studying spatial navigational abilities in rats. It requires that rats swim to find a platform located just below the surface of the water in a swimming pool, and rats will learn and perform the task readily without being subject to nutrient deprivation. A novel adaption of the task, in which rats are shown to form a place learning-set, is described in the present paper. The learning-set paradigm can be used for the repeated evaluation of spatial navigation abilities in the same animals over a long period of time. The procedure is based on the finding that once trained, rats can acquire a new place response each day. Each new response can be learned within one or two trials, given within the time period of a few seconds, and once acquired, the response can be retained for a number of days, or until the problem is changed. The procedure can be usefully applied to the study of recovery of function following brain damage, the study of memory processes following brain damage, the changes in memory processes accompanying aging, or it can be used for the screening of pharmacological compounds, etc. The technique may be especially useful for the study of the performance of individual rats.