The sonochemical degradation of 17B-estradiol (E2) and 17a-ethinylestradiol (EE2) in water and wastewater was investigated at ultrasonic frequency of 850kHz. The effects of pH, initial concentrations, temperature, power and dissolved organic carbon were examined. The results obtained indicated that the rate of ultrasonic degradation of E2 and EE2 in water and wastewater is influenced by the pH, power, air sparging, and the dissolved organic content of the aqueous solutions. Mass degradation rates of E2 and EE2 per kilowatt ranged from 1.7 mg/kW-1 to 4.0 mg/kW-1 at varying process parameters. The degradation process followed the pseudo-second order kinetic model with rate constant of 1.71×10−2 min−1 at 25oC. The value for activation energy (Ea = 15.21 kJ mol−1) obtained from Arrhenius type plot, indicated that the ultrasonic degradation of steroid hormones is thermodynamically feasible, and does not progress only on radical reactions but other intermediate reaction processes. In wastewater the higher dissolved organic carbon significantly reduced the effectiveness of degradation of the E2 and EE2 showing that ultrasound treatment will be more effective as a tertiary treatment option in wastewater applications.