Intracranial tuberculomas can sometimes develop or increase in size despite administration of appropriate therapy. We report the case of a child whose intracranial tuberculomas paradoxically enlarged while therapy was being administered, and we review 23 other cases in which tuberculomas increased in size or number and 17 cases in which tuberculomas appeared during therapy. These phenomena generally occurred within 3 months of the start of therapy. All but four patients had neurological deterioration that prompted obtaining a repeated computed tomographic scan. One patient died, about one-fourth of patients had residual neurological symptoms, and less than one-third of the patients required surgical intervention. Most patients received a 12-18 month course of antituberculous therapy. Adjunctive therapy with steroids appears to diminish neurological symptoms and may improve outcome. Paradoxical enlargement or development of tuberculomas usually does not represent failure of antituberculous therapy; the most likely explanation for these phenomena is an interaction between the host's immune response and the direct effects of mycobacterial products.