Electroconvulsive therapy (ECT), even more than 80 years since its introduction, continues to be the most effective treatment for severe mental disorders. Croatian psychiatrists have used ECT since 1940s. Today it is performed only at the University Hospital Centre Zagreb, predominantly in patients with schizophrenia. Extensive research reported numerous biological effects of ECT, which contribute to its antidepressant, antimanic, antipsychotic, anticonvulsive and antiparkinsonian effects. Convulsions trigger changes in the cerebral blood flow and metabolism, increase the permeability of the blood-brain barrier, modulate glutamatergic, GABAergic, serotonergic, noradrenergic and dopaminergic neurotransmission, affect hormone secretion, gene expression, stimulate neuroplasticity, and eventually induce brain structural changes. Some of these effects are short-lasting and others, such a neuroplasticity, last for at least several months. While ECT is generally considered a low-risk medical treatment, patients with severe somatic comorbidity require careful risk-benefit assessment. The most commonly observed adverse events are transient forgetfulness and headache. Prior to initiation, candidates undergo comprehensive diagnostic evaluation according to international standards. The procedure is performed by an interdisciplinary team, consisting of psychiatrist, anesthesiologist, and psychiatric and anesthesiological nurses. The application of general anesthesia enables rapid loss of consciousness, short-time muscular relaxation, suppression of hyperdynamic response to electrical current and fast recovery of breathing and awareness. Recently, the Croatian expert group has proposed national guidelines for the ECT treatment. Due to its efficacy in both treatment-refractory and very severe symptomatology, ECT might be of a great benefit in carefully selected patients.