Daphnia magna is one of the most commonly used model organism to assess toxicity of wide range of pharmaceuticals such as antibiotics, anticancer drugs, antidepressants, anti-inflammatory drugs, beta-blockers and lipid-regulating agents. Currently, daphnia toxicity tests based on immobilisation and lethality standardised by OECD, acute immobilisation test and reproduction test, are mainly used in toxicological studies. Detailed analysis of Daphnia biology allows distinguishing the swimming behaviour and physiological endpoints such as swimming speed, distance travelled, hopping frequency, heart rate, ingestion rate, feeding rate, oxygen consumption, thoracic limb activity which could be also useful in assessment of toxic effects. The advantage of behavioural and physiological parameters is the possibility to observe sublethal effects induced by lower concentrations of pharmaceuticals which would not be possible to notice by using OECD tests. Additionally, toxic effects of tested drugs could be assessed using enzymatic and non-enzymatic biomarkers of daphnia toxicity. This review presents scientific data considering characteristics of D. magna, analysis of immobilisation, lethality, reproductive, behavioural, physiological and biochemical parameters used in the toxicity assessment of pharmaceuticals. The aim of this paper is also to emphasize usefulness, advantages and disadvantages of these invertebrate model organisms to assess toxicity of different therapeutic classes of pharmaceuticals. Also, various examples of application of D. magna in studies on pharmaceutical toxicity are presented.