The effect of Fenton-like and photo-Fenton pre-treatment on the toxicity and biodegradability of Procaine Penicillin G (PPG) antibiotic formulation effluent was investigated. Fifty-six percent and 44% COD removal efficiencies were obtained and the BOD5/COD ratio increased from 0.10 to 0.45 and from 0.10 to 0.24 after application of photo-Fenton and Fenton-like processes, respectively. Overall TOC removal efficiencies were in the range of 42-35%. Based on the acute toxicity test results using Daphnia magna the photo-Fenton-like and Fenton-like processes were suitable methods for complete detoxification of PPG effluent. Pre-treated PPG effluent did not cause any inhibitory effect on the activated sludge process.