Seventy-five women, of whom 30 had received postoperative radiotherapy, were tested for range of motion (ROM) and shoulder strength with a goniometer and an isokinetic device (Orthotron II), respectively. On the individual level, irradiated patients exhibited significantly reduced range of motion (varying from p < 0.05 to p < 0.001) for all movements compared with the non-operated side. In contrast, in the non-irradiated patients only flexion was significantly reduced (p < 0.05). The same individual pattern was evident for shoulder strength where all movements except external rotation were significantly reduced in irradiated patients (varying from p < 0.05 to p < 0.001). Non-irradiated patients exhibited a significant reduction in shoulder strength for flexion and abduction (p < 0.05), whereas other movements were less affected. The observed differences in ROM and strength were less pronounced when analyzed on a group level, but were still significant for ROM (p < 0.001) for flexion and abduction. Group level analysis also showed reduced shoulder strength for all movements but only rotation was significantly (p < 0.01) impaired.