Infantile spasms (IS) is a severe developmental and epileptic encephalopathy, occurring mainly in children aged 3-18 months. IS have multiple aetiologies, and the treatment differs accordingly. Early diagnosis and treatment may improve the outcome, but many patients are initially misdiagnosed. Evaluation includes seizure semiology, electroencephalography, cerebral magnetic resonance imaging and genetic and metabolic testing. Treatment varies among centres, and initial treatment may include vigabatrin and/or corticosteroids. In recent years, as summarised in this review, knowledge has substantially increased regarding genetic aetiologies and treatment regimens.