Despite the absence of a clear-cut rationale for their use, corticosteroids are widely employed in the treatment of dengue shock syndrome. Previous comparative therapeutic trials have yielded contradictory results. Resolution of this therapeutic controversy has been attempted with a double-blind evaluation of the clinical effect of steroid administration in dengue shock syndrome. Placebo or a single dose of hydrocortisone hemisuccinate, 50 mg/kg of body weight, was administered randomly to 97 physiologically treated patients with dengue shock syndrome. The severity of disease on admission to the hospital and the effectiveness of treatment were quantified by a World Health Organization scoring system. The response to therapy as measured by mortality, duration of shock, and amount of replacement fluids required was virtually identical in 47 children who were and 50 children who were not treated with steroids. The comparison groups were composed of children similar in age, sex, and severity of illness. It is concluded that hydrocortisone is of no value in the treatment of dengue shock syndrome. Reliance should be placed on appropriate supportive and physiologic therapy.