Metabolic acidosis is the most common disturbance of acid-base balance among the critically ill of all ages, usually due to increased lactate production consequent on inadequate tissue perfusion and/or hypoxemia. The condition is characterized by primary reduction in bicarbonate and pH revealed during arterial blood gas analysis. For more than 50 years, standard care of patients suffering metabolic acidosis, whatever its cause, has included iv administration of the base sodium bicarbonate to correct the acidosis. Although sodium bicarbonate is certainly effective in restoring pH towards normal, in recent years doubt has been cast on the notion that it is necessary to artificially restore pH, and controversy has surrounded the ritual administration of sodium bicarbonate to patients with metabolic acidosis. This controversy is revisited in a recently published paper from two US pediatricians who robustly argue that sodium bicarbonate has no benefit and may cause harm to neonates. A major plank of their argument is the lack of evidence that bicarbonate is beneficial. The treatment was introduced before evidence-based medicine was the norm and the few randomized trials that have been conducted in more recent times have in general failed to show benefit. The article includes an historical perspective on bicarbonate use, and a critical assessment of the rationale for bicarbonate therapy. There follows a brief overview of metabolic acidosis in neonates and a discussion of current evidence about the potential risks and questionable evidence of benefit of bicarbonate therapy for neonates specifically. Evidence that bicarbonate therapy may actually be harmful to neonates is reviewed. Possible adverse effects include intracranial hemorrhage and worsening intracellular acidosis resulting in impaired cell function. In conclusion the authors state that clinicians should "resist the common impulse to administer bicarbonate to infants with metabolic acidosis". The focus should not be correcting the extracellular pH, but treating the underlying cause of acidosis.