Bioavailability of iron bis-glycine chelate added to water and milk was studied using a double-isotopic method in two groups of 14 women aged 33-51y. Iron absorption of an aqueous solutions with 15 mg/L of elemental iron as either iron bis-glycine or ferrous ascorbate were not significantly different(27.7% and 23.9%, respectively). There was significant correlation between(log) iron absorption of iron bis-glycine and (log) serum ferritin (r= -0.60, p<0.03) and (log) iron absorption of ferrous ascorbate (r=0.71, p<0.006), showing conclusively that iron bis-glycine chelate bioavailability is indeed controlled by iron stores. Iron absorption of iron bis-glycine given in milk, standardized to 40% absorption of the reference dose of ferrous ascorbate, was significantly lower (p<0.001) than that observed in an aqueous solution, with values of 11% and 46%, respectively. Iron absorption of iron bis-glycine given in milk increased significantly(p<0.05) to 15% with the addition of 100 mg/L of ascorbic acid. The good availability of iron bis-glycine makes this compound a good alternative to be considered in iron fortification programs.