This paper investigates the biodegradability of wastewaters originating from a paracetamol active ingredients production factory. Experimental biodegradability tests are performed under aerobic and anaerobic conditions. In this pharmaceutical plant, approximately 1 m(3) of wastewater is generated per ton paracetamol produced. According to the results of conventional characterization, a strong wastewater that is almost totally soluble in nature is produced. ED50 value for raw effluent is determined to be 6.7 % at 30 mm showing significant toxicity towards the marine bacterium Vibrio fischeri. Aerobic and anaerobic treatment alternatives are comparatively evaluated in terms of the lowest achievable COD levels after biotreatment. Aerobic treatment yields a residual COD of 355 mg/L. The discharge standards of 600 mg/L can be complied with the usage of an aerobic treatment unit. Application of anaerobic treatment, on the other hand, is not efficient in removing organics from these effluents. Almost up to 87 % of the COD is recalcitrant under anaerobic conditions resulting in around 16000 mg/L of COD at the outlet of anaerobic treatment. Therefore, aerobic treatment must be favoured over anaerobic one before discharging these effluents to the sewerage system.