Introduction. Numerous recent studies show that misuse of stimulants by individuals without ADHD (Attention Deficit Hyperactivity Disorder) has increased over last years, in order to enhance cognitive performance. This is especially popular among students. Hence, the need to assess the effects of methylphenidate on healthy brain (without ADHD), as well as the associated adverse reactions, arises. Aim of the study. To evaluate the prevalence of methylphenidate (MPH) usage among medical students, to emphasize pharmacological effects and adverse reactions. Materials and methods. A self-administered, anonymous questionnaire was distributed in online and sheet forms to students of the ungraduated medical programme. The literature review on stimulants misuse has been performed, including search of following databases: PubMed, ResearchGate, neurology.com, etc. Results. 114 questionnaires have been completed, including: 34 – online and 80 – on sheets. Approximately 14,0% (16 of 114) of surveyed students have used MPH for non-medical purposes. Most of them used it to enhance their ability to concentrate 63,64 % (7 of 11). Next adverse reactions were mentioned: tachycardia/High Blood Pressure (8 of 13); anxiety/fear (5 of 13); headache (5 of 13); seizures/convulsions (2 of 13); sleep disorders (9 of 14). Recent studies put college students’ nonprescription use of stimulant drugs — Ritalin and amphetamines such as Adderall and Dexedrine — at rates anywhere between 14 and 38 percent, depending on the type of college and age of student. Main purpose of usage is enhancing the ability to concentrate and memorize. Most frequent adverse reactions (>10%) are: psychiatric disorders, insomnia, irritability, decreased appetite, headache, infections. Conclusions. The prevalence of MPH usage among medical students fits in general statistics. The primary reason of usage also coincides. Some respondents have not mentioned the emergence or absence of adverse reactions. This may be due to refusal to answer or unawareness of the adverse reactions. The literature review revealed that benefic effects of MPH are observed in individuals with lower ability of concentration/memorization, showing that the drug is more effective at correcting deficits than “enhancing performance”. In individuals with good ability of concentration/memorization enhanced motivation has been observed, although associated with higher incidence of adverse reactions.