One of the most endearing characters in English literature is Tiny Tim, the crippled son of Ebenezer Scrooge's clerk, Bob Cratchit. Yet the nature of Tiny Tim's multifaceted and implicitly reversible illness is a mystery and open to debate and speculation. From details of the original manuscript and the eight film versions, it is possible to construct a differential diagnosis for Tim's short stature, asymmetric crippling disorder, and curious intermittent weakness that would lead to his death, if untreated, within a period of 1 year. Following the ghostly visitations, Scrooge vows to assist the struggling Cratchit family financially, thereby making available the best medical care money could buy. From review of pediatrics texts from 1830 to 1850, a recommended treatment plan would have included (1) general measures such as country air and exercise, and fish oils such as cod and halibut (vitamin D), and (2) specific treatments of tonics (containing combinations of belladonna, opium, sodium bicarbonate, sodium citrate, and potassium chloride) emphasizing alkalis, and splinting and bracing the limbs. Such treatments with vitamin D and alkalinization with sodium bicarbonate and sodium citrate suggest the plausible speculation that Tiny Tim had renal tubular acidosis (type I), a disorder that is characterized by growth failure and, if left untreated, complicated by osteomalacia with pathologic fractures, hypokalemic muscle weakness and periodic paralysis, nephrocalcinosis leading to renal failure, and death. I propose that Tiny Tim had distal renal tubular acidosis (type I).