Meldonium is used clinically as an anti-ischaemic drug to treat myocardial infarction and chronic heart failure, and it had become a news making substance after the banning several elite athletes including Maria Sharapova from competitions. Despite this, the majority of possible biological effects of meldonium remained unexplored. We tested two effects, I) on the circadian clocks of fruit fly (Drosophila melanogaster) and II) on the process of pea seed germination (Pisum sativum). I. Comparison of the effects of photoperiod and meldomium on the circadian rhythm of locomotor activity during the 2nd and 3rd days in constant darkness revealed the expected effect of the previous photoperiod whereas meldonium in concentrations ranged from 1 (5 mg/kg) to 10,000 therapeutic doses failed to alter the mechanism of the fly’s circadian clocks. II. A treatment with meldonium in very high concentration (2000 therapeutic doses) negatively affected the process of germination of pea seeds.