Thirty-two patients with general paresis were inoculated with a small number of Plasmodium vivax trophozoites— 1, 10, 100, 250, 500, and 1000—in an attempt to correlate the resultant infection and therapeutic result with the dosage of parasites. The results indicated that there was a relationship between the dosage and incubation period, and that the character of the infection once established was independent of the range of dosage employed. It is suggested that a more uniform and predictable onset of infection for therapeutic purposes may be obtained by the use of a standardized small dose of parasites than is possible by the artificial methods generally used. Malaria infections established by injecting these small counted numbers of trophozoites seemed, on the whole, to be better tolerated by the patient with general paralysis, and usually better therapeutic results were obtained. Finally, it is felt that if this or a similar standard method could be universally employed, it would be possible to have a more accurate analysis and comparison of the results obtained from the many institutions where malaria is used for the treatment of general paralysis.