<p>Social isolation is a moderate stressor whose long-term effect can lead to the development of mental disorders and an increase in mortality from various causes, especially in older people. Social isolation is also a stress factor in animals. Here we report studies of the effects of prolonged (14 weeks) isolation on non-associative learning in outbred Wistar rats and the genetically related normotensive WKY rats and spontaneously hypertensive SHR rats. Experiments were performed on males aged 9–10 months, some of which were placed in individual cages, the rest being kept in groups. Non-associative learning (habituation) was studied in the open field test. Short-term habituation was assessed in terms of changes in locomotor activity and the number of rearings during the first session. Long-term habituation was assessed by repeat testing 96 h later. Wistar rats displayed both short-term and long-term habituation; isolation impaired both forms. Control WKY rats displayed short-term habituation and impairment of long-term habituation, while SHR rats demonstrated total impairment of non-associative learning. Long-term isolation had no additional effect on the behavioral parameters studied in WKY and SHR rats. Thus, non-associative learning was impaired in hypertensive SHR rats, and isolation, which impaired non-associative learning in Wistar rats, did not affect this type of learning in genetically related WKY and SHR rats.</p>