The Shigella carrier state was eliminated from its nonhuman primate host, Macaca mulatta. Each of 31 animals was treated twice a day for ten consecutive days with 16 mg trimethoprim and 80 mg sulfamethoxazole delivered via stomach tube. Fresh rectal swab and stool enrichment cultures were taken for seven consecutive days as well as the 35th and 78th days after treatment, and all were negative for shigellae. In addition, no clinical signs of shigellosis were observed during or following an extensive period of stress.