Ketoprofen (KET) is a nonsteroidal anti-inflammatory and analgesic drug commonly used in human and veterinary medicine. This compound is detected in aquatic reservoirs however, little is known about its influence on cladocerans. Therefore, the aim of our study was to determine the influence of KET at concentrations of 0.005 mg/L, 0.05 mg/L, 0.5 mg/L, 5 mg/L and 50 mg/L on behavioral (swimming speed, hopping frequency) and physiological endpoints (heart rate, thoracic limb activity, mandible movements) of Daphnia magna after 24 h and 48 h exposure. The study showed that swimming speed frequency was decreased after 24 h and 48 h at all the concentrations used in the experiment. Hopping frequency was also inhibited, however the lowest amount of the drug induced transient increase of the parameter after 24 h and its subsequent decrease to the control level after 48 h. Although after 24 h of the exposure physiological parameters: heart rate, thoracic limb activity and mandible movements showed slightly lower sensitivity to KET than the behavioral endpoints: were found to be inhibited after 48 h. The results revealed that both behavioral and physiological endpoints of daphnids responded to KET also at the environmental level, therefore in natural conditions this drug should be considered as a hazardous toxicant to crustaceans.