The present invention relates to production of fermentable sugars from lignocellulosic material by enzymatic conversion. The fermentable sugars are useful e.g. in the production of bioethanol. Novel polypeptides having endoglucanase activity, polynucleotides encoding them and vectors and host cells containing the polynucleotides are disclosed. A method for treating cellulosic material with the novel endoglucanase as well as uses of the enzymes and enzyme preparations and a method of preparing them are described.