A method and a network node (110; 400) for scheduling of resources to radio bearers associated with wireless devices (120, 121, 122) served by a base station (110) in a cell (115). The network node (110, 400) and the base station (110) operating in a wireless communications system (100) applying carrier aggregation. A first group of one or more of the wireless devices (120, 121) is served in the cell (115) as primary serving cell and a second group of other one or more of the wireless devices (122) is served in the cell (115) as a secondary serving cell. The network node (110, 400) assigns higher priority to respective radio bearer associated with the first group than to respective radio bearer associated with the second group based on that the second group is served in the cell (115) as a secondary serving cell. The network node (110, 400) then schedules (302) the resources to the radio bearers based on the assigned priorities. Simple implementation and efficient utilization of benefits from carrier aggregation are enabled.