Azo dyes, which represent about one- half of all dyes in common use, are also the most common synthetic colorants released into the environment. Bioremediation of azo dyes in textile waste effluents by fungi is an alternative to conventional methods for its relatively low expense involved and environmental friendly nature. However, knowledge of fungal degradation mechanisms of organic pollutants including dyes is still lacking. This study employed a comprehensive approach for investigating the degradation of carefully chosen model azo dyes by white rot fungi using a wide spectrum of analytical techniques. The metabolites of ionized and unionized azo dyes were identified and quantified. Possible pathways leading to formation of these products are discussed.