Timely diagnosis of musculoskeletal infections is essential to prevent severe complications of this disease. Important symptoms that lead to the diagnosis include high fever, malaise, local pain and loss of function of the involved extremity. In the case of arthritis, swelling of the affected joint may develop quickly in the course of disease. Imaging techniques include ultrasound and MRI. Both are useful in determining the exact site of infection. Infectious parameters, C-reactive protein and/or sedimentation rate of erythrocytes (ESR) are used in following disease activity during treatment. The gold standard for diagnosing musculoskeletal infection is microbiological isolation of the organism. Bone-biopsy of an involved metaphysis or aspiration of joint-fluid gives the highest chance of a positive culture. Usually S. aureus is the causative micro-organism, although specific underlying diseases may predispose to other bacterial infections. Antibiotic treatment is aimed at the most likely causative micro-organism. In some instances surgical treatment is necessary, especially in cases of focal and chronic osteomyelitis and when the adjacent joint is involved in the inflammatory process. Collaboration between paediatrician and orthopaedic surgeon is essential to achieve the best treatment for the patient.