Methyl violet and crystal violet are triphenylmethane group of dyes that are extensively used for dying nylon, silk, wool and cotton. Leather and paper industries are also major consumers of these dyes. Due to poor dyeing procedure, enough amounts of dye effluents flow out from textile units. According to earlier research data, a little amount of these dye effluents can completely change the physico-chemical properties of natural water resources and may cause many serious health issues. In the present work, the decolourisation of crystal violet and methyl violet by Aspergillus fumigatus MTCC 3002 and Aspergillus niger MTCC 478 has been investigated. It was observed that Aspergillus fumigatus MTCC 3002 could decolourise 79% of crystal violet and 67% of methyl violet grown with 20-100 μM dye concentration at pH 3.00 with additional glucose and sodium nitrate. In contrast, Aspergillus niger MTCC 478 was found to decolourise 54% of crystal violet and 76% of methyl violet grown in the similar condition. With glucose as additional carbon source the decolourisation percentage was comparatively more. The decolourisation ability of Aspergillus fumigatus was more for crystal violet and that of Aspergillus niger was comparatively more for methyl violet. The decolourisation of these dyes and other related compounds that pose environmental problems warrants further screening of organisms that could be applied in an eco-friendly and cost effective manner for bio-degradation of various environmental pollutants.