The developmental toxicity of a commercial formulation of herbicide containing a mixture of 2,4-D, MCPP and DICAMBA plus inactive ingredients in mice was investigated. Pregnant mice were exposed to one of four increasing doses of the herbicide mixture diluted into their drinking water, either during preimplantation and organogenesis or only organogenesis. The offspring were allowed to lactate and grow without herbicide exposure. At six weeks, they were tested for immune (capacity to make antibodies against a foreign protein) and encocrine (thyroxine blood concentration) function as well as behavioral (wheel running activity) status. Exposure to the herbicide mixture caused dose- and sex-dependent changes in immune and endocrine function but no alterations in wheel running behavior. A non-linear decrease in litter size, as well as a decrease in birth weight and crown-rump length at higher doses was also determined.