Shock is defined as circulatory failure, inadequate delivery of substrates and oxygen to the tissues, and restricted removal of wastes from the body. As oxygen delivery is impaired, the cell must switch from aerobic metabolism to the much less efficient anaerobic metabolic pathway, with resulting production and accumulation of lactic acid. The major categories are hypovolemic, distributive, cardiogenic, septic and obstructive. The frequency of the different causes of shock varies around the world, but most common are hypovolemia and infection. Clinically shock presents with primary disorder symptoms, compensating body response and organ hypoperfusion. Diagnosis is made in first 60 seconds based on clinical appearance of child. The most important signs are tachycardia, small, weak pulse, prolonged capillary refill time, oliguria, altered mental status, tachypnea, pale, cool skin. Hypotension is late and bad sign of circulatory failure. Vital laboratory study for assessment of circulatory state is measurement of serum lactate levels. Treatment starts with primary evaluation of child (AVPU-ABCDE). After that, patient must be adequately oxygenated and peripheral vascular access must be ensured. Finally, therapy of choice is rapid and aggressive fluid resuscitation, and if necessary vasopressors, blood derivatives and bicarbonates.