Wastewater from a pharmaceutical formulation facility (TevaKS, Israel) was treated with a biological activated-sludge system followed by ozonation. The goal was to reduce the concentrations of the drugs carbamazepine (CBZ) and venlafaxine (VLX) before discharging the wastewater to the municipal wastewater treatment plant (WWTP). Both drugs were detected at extremely high concentrations in TevaKS raw wastewater ([VLX]=11.72±2.2mg/L, [CBZ]=0.84±0.19mg/L), and resisted the biological treatment. Ozone efficiently degraded CBZ: at an O3 dose-to-dissolved organic carbon ratio of 0.55 (O3/DOC), the concentration of CBZ was reduced by >99%. A lower removal rate was observed for VLX, which was decreased by ∼98% at the higher O3/DOC ratio of 0.87. Decreasing the pH of the biologically treated effluent from 7 to 5 significantly increased the ozone degradation rate of CBZ, while decreasing the degradation rate of VLX. Ozone treatment did not alter the concentration of the effluent's DOC and filtered chemical oxygen demand (CODf). However, a significant increase was recorded (following ozonation) in the effluent's biological oxygen demand (BOD5) and the BOD5/CODf ratio. This implies an increase in the effluent's biodegradability, which is highly desirable if ozonation is followed by a domestic biological treatment. Different organic byproducts were formed following ozone reaction with the target pharmaceuticals and with the effluent organic matter; however, these byproducts are expected to be removed during biological treatment in the municipal WWTP.