The objective of this study was to compare trace elements in milks of four species. Milk samples of 4 ml or more were obtained from guinea pigs, dairy cattle, horses, and humans. The milks were analyzed for the trace elements Al, B, Ba, Cu, Fe, Li, Mn, Mo, Si, Sr, Ti, and Zn by inductively coupled argon plasma spectroscopy. Zinc ranged from more than 4 ppm in guinea pig milk to less than 2 ppm in mare milk. Strontium was over 1 ppm in the milk of guinea pigs and less than .1 ppm for the human. Iron ranged from over .7 ppm for the guinea pig to less than .2 ppm for the cow. Copper was over .5 ppm in guinea pig milk and only .05 ppm for cow milk. Boron ranged from .59 to .10 ppm, Si from .58 to .16 ppm, Al from .45 to .10 ppm; and Ba from .22 to .08 ppm in milks of the four species studied. Titanium ranged from a trace to .11 ppm. Lithium, Mn, and Mo all were less than .04 ppm. Milk Mn was surprisingly low relative to bodily needs.