The present invention relates to a method and a base station (14, 700)for load balancing in Semi-Persistent Scheduling, SPS transmission. The method can comprise to activate downlink or uplink SPS transmission for a User Equipment (12, step 204), and to obtain information about transmission load comprising SPS transmission or HARQ ACK/NACK responses to SPS transmissions, on a Physical Shared or Control Channel (steps 206; 402; 406; 502, 504, 508, 510). Based on the obtained information it is determined for which subframe within aduration of T subframes, the transmission load comprising SPS transmission or HARQ ACK/NACK response to SPS transmissions, on a Physical Shared Channel or on a Physical Control Channel is the lowest within the duration of T subframes (steps 208; 404; 408; 506, 512, 514). SPS transmission is then scheduled to be valid in the determined subframe having the lowest SPS transmission load on the Physical Shared Channelor to be valid in a subframe causing the HARQ ACK/NACK responses to the SPS transmissions to be transmitted in the subframe having the lowest of HARQ ACK/NACK responses to the SPS transmissions, within the duration of T subframes (step 210).This load balancing provides a number of advantages comprising less postponed scheduling, less unused subframes and less collisions on said channels.