The growth of human consumption from year to year increases the use of pharmaceuticals in everyday life. This has extremely negative effect on environment, especially the water, causing the pollution. The problem occurs in the treatment of such waste water because the water, which contaminated with pharmaceuticals, is very difficult to process with conventional methods of treatment. All these facts, and the lack of legal regulations that prescribe the maximum permissible concentrations of pharmaceuticals in environment, prompted the scientists and numerous experts on doing researches which are focused on the development of modern technologies for wastewater treatment. The aim of this study was to determine toxicity of pure active compounds of anthelmintics (albendazole, febantel, praziquantel) and antibiotics (cefdinir, nitrofurantoin). Before determining toxicity of pharmaceutical active substances in environment, it is important to determine the toxicity of pure active components to help track the toxicity of their metabolites and degradation products in environment. To determine the toxicity was applied bioluminescent method DIN 38412-L-34 that as test organisms used Vibrio fischeri bacteria which are sensitive to organic contaminants which presence causes a reduction of their luminescence. Measurements have shown that all pharmaceuticals with higher concentrations of pure component cause inhibition of bacterial culture. What concentration will be taken as the limit one depends on the severity of the observed effect. As for the most pharmaceuticals is not known action after their use, it is necessary to implement more and more such measurements, especially for antibiotics and estrogens, which are suspected to persist in environment, either due to disability of biodegradation or continuous discharge.