The amount of spontaneous change in aphasia was quantified in 44 right-handed patients who were aphasic following a first and unihemispheric stroke. All were initially tested less than 14 days after onset and were reevaluated at a mean of 30 days. The Porch Index of Communicative Ability was administered for objective and precise measurement. Forty-one of the patients demonstrated significant improvement, a finding which must be taken into account in evaluating any claims for effectiveness of speech therapy.