Statins, the cholesterol lowering drugs, are one of the most prescribed medicaments at all. Despite this fact, great variety of side effects – including cognitive, behavioural and motoric changes – is discussed in many studies. However, the variability of results of former studies is enormous and thus, the problem remains unsolved. The aim of this project is to study: 1) behaviour of rats in a wide battery of tests, 2) correlations between the changes of SERT activity, levels of cholesterol and behaviour of rats, 3) effect of dose or length of drug administration. For this study we used atorvastatin in different doses and lengths of administration. Wistar rat males (n=48) were divided into 6 groups (n=8 for each) – 2 control groups, 4 groups with statin administration. Statin was administered in long (34 days) or short (21 days) administration protocol; in dose of 20 mg/kg, 10 mg/kg or in mixed design. Statins were administered to the rats orally in jelly mixture once a day. Behavioural tests were made before and after administration what allows us to compare the changes in performance of animals. We used behavioural tests to test impulsivity, anxiety and depression-like behaviour (OF, EPM, FST), cognitive tests (MWM, allothetic active place avoidance test) and locomotor tests (beam walking, rotarod). At the end of the experiment we collected samples for biochemical analysis. Analysis of results showed no significant effect of application on performance in MWM. No significant motoric impairment was found. We found a significant effect of long administration of low dose of atorvastatin on performance in reversal learning in AAPA (p≤0,01). There was also trend in performance in OF test and EPM after the administration of high dose of atorvastatin. In conclusion, we found out that prolonged administration of atorvastatin in rats may cause some slight behavioural and cognitive changes. One the other hand, in most of the test the effect was not significant. However, we found marked inter-individual differences in animals and also significant effect of used cohorts (differing in age). The question is whether these effects may mask the effects of statins. Together with ambiguous results of previous experiments it highlights the need for additional experiments, what may better explain potential behavioural and cognitive changes.