Both residual lignins and lignins isolated from the pulping liquor of 20 l batch cookings of spruce chips according to the organocell process were subjected to HPSEC. Checking the resulting Mn-values by vapor pressure osmometry confirmed the HPSEC data except for first stage lignins with short cooking times, where the different elution behavior caused by high portions of organic nonlignin substances is held responsible for these discrepancies.