Information concerning the epidemiology of acute osteomyelitis (OM), septic arthritis (SA) and concurrent OM and SA in children is limited. The aim of this study was to describe the epidemiology of OM, SA and concurrent OM and SA in children. During the 4 years of the study, 63,999 patients were admitted to the Children’s Hospital, Tehran, Iran. We identified 111 patients with OM and/or SA during the 4‑year period. There were 72 cases of OM (11 cases per 10,000 children) and 90 cases of SA (11 cases per 10,000 children). Concurrent OM and SA accounted for 0.17% of all cases (n = 51). The erythrocyte sedimentation rate and C‑reactive protein were elevated in the majority of both infections. Staphylococcus aureus was the most frequent pathogen responsible for both OM and SA in any age group. The lower limb was the most frequently affected (femur: 33/72, 46%; tibia or fibula: 22/72, 31%; foot: 5/72, 7%). The most frequent involved joints were hips (n = 31, 34%) and knees (n = 31, 34%). The present study showed high frequency of patients with concurrent SA and OM. Therefore, prompt recognition and proper diagnosis of pediatric OM and SA is highly recommended.