Acute febrile toxoplasmosis acquired accidentally by needle scratch in the laboratory led to a local ulcer on the finger with bilateral axillary and cervical lymphadenopathy and a fine erythematous rash but no pneumonia. Toxoplasma was isolated from the blood stream 9 and 10 days after infection, and antibodies developed. Chemotherapy consisting of 25 mg. of pyrimethamine and 4 Gm. sulfadiazine was instituted on the 9th day and continued for 39 days. By the 11th day the patient was afebrile and toxoplasma was no longer isolated. Moderate leukopenia and thrombocytopenia were antagonized by 5 to 15 mg. of leucovorin calcium and two yeast cakes daily. Thus, the drug-induced hematological deficiency was reversed by substitution of the inhibited vitamin without need of discontinuing the primary objectve, antitoxoplasmic chemotherapy.