Denosumab, a bone-modifying agent, reduces the risk of skeletal-related events in patients with bone metastases from solid tumors and is generally well tolerated. However, hypocalcemia, osteonecrosis of the jaw (ONJ) and atypical fracture are potential and important toxicities of denosumab therapy that require attention. In pivotal phase III trials in patients with bone metastases from solid tumors, the incidence of hypocalcemia was 9.6% in denosumab-treated patients, with most events being asymptomatic, grade 2 and resolving by week 4. Established hypocalcaemia requires additional short-term calcium and vitamin D supplementation and, if severe, administration of intravenous calcium. ONJ was reported in 1.8% of patients receiving denosumab over 3 years in these trials. Involvement of an experienced oro-maxillary surgeon is important if ONJ is suspected. Atypical fractures were rare in a large study of denosumab using the dose and scheduling approved for the treatment of osteoporosis. To prevent toxicities, patients should maintain calcium and vitamin D supplementation, good oral hygiene and regular dental reviews throughout treatment. This article presents case studies from our clinical practice and discusses the pathophysiology of these toxicities along with guidance on prevention, diagnosis and management.