The present invention provides a method for preparation of a lyophilized formulation of an anti-CD 20 antibody as well as to a lyophilized formulation of an anti-CD 20 antibody, comprising an anti-CD 20 antibody and having a residual moisture content in the range of 1% to 10%. The present invention also relates to the reconstituted formulation obtained by the method described herein, the use of said antibody formulation as a medicament, the use of the lyophilized formulation for the preparation of a medicament and a method of treating a patient.