Until recently, there were no herbicides with broadleaf weed control activity that could be applied postemergence over-the-top that would not adversely affect cotton growth, development, or yield. Ammonium thiosulfate has been marketed to reduce MSMA effects on cotton; however there is no published data to confirm this use. Field experiments were conducted in 1997 and 1998 at the Prattville Experiment Field in Prattville, Alabama and the Wiregrass Substation in Headland, Alabama to determine if ammonium thiosulfate additions to MSMA would affect weed control, lessen MSMA-induced cotton injury, lessen the fruiting and maturity delay on cotton caused by MSMA, and lessen the MSMA-induced yield reduction in cotton. Treatments included a complete factorial combination of MSMA (0, 1.12, and 2.24 kg/ha) and ammonium thiosulfate (Sul-Max 15) (0, 1.75, and 3.50 L/ha). Treatments were applied before cotton was at the pinhead square stage and the weeds were 5 cm tall. Weeds evaluated were sicklepod [Senna obtusifolia (L.) Irwin & Barneby], morningglory spp. (Ipomoea spp.), yellow nutsedge (Cyperus esculentus L.), and Texas panicum (Panicum texanum Buckl.). Crop injury, cotton maturity, and yield were also evaluated.