Objective: This study aimed at optimizing the amplification conditions of the B1 gene (35 copies in the genome) of T. gondii in cases of possible brain toxoplasmosis. Materials and methods: DNA was extracted from the peritoneal exudate of mice inoculated with the RH strain of T. gondii. Total exudate volume was 17 mL with a concentration of 1x107 parasites/mL. PCR conditions for the B1 gene were further optimized.Results: Serial dilutions from 1x106 to 1x10-1 parasites/mL were needed for amplifying a fragment of 132 bp . This set the detection limit for 1 T. gondii tachyzoite.