Undyed and reactive-dyed cotton fabric was treated with a whole cellulase at tumbling speeds up to 120 Hz with and without steel balls. It was found that the fabric weight loss strongly depended on the extent of agitation up to a tumbling speed of 78.8 Hz, while above 78.8 Hz weight losses did not increase further. The effects of mechanical action and enzymatic reaction were distinguished by the use of scanning electron microscopy. Color strength values increased after the enzymatic treatment, although seemingly less dye was found in the cotton sample. This suggests possible savings in dye costs. Of the surfactants under investigation, only the cationic and, to a much lesser extent, the nonionic compound had a promoting effect on the enzymatic hydrolysis, while the anionic compound reduced the efficiency of the enzymes considerably. The sequence of application of enzyme and surfactant played some role in most cases.