The influence of stage of lactation on the moisture. total soilds, ash, calcium, phosphorus and Ca/P ratio of human milk was studied. A total number of 32 lactating mothers provided 101 samples collected at 4 consecutive stages of lactation : days o to 5 postpartum(colostrum); days 6 to 10 postpartum(transitional): days 25-35 postpartum(mature). and days 55-70 postpartum(mature). Moisture and total solids concentrations showed a little but significant difference at the 25-35 day stage as compared with those of colostrum and then remained stable, but ash levels decreased significantly with the elapse of lactation period. Calcium levels increased significantly from colostrum to transitional milk stage with a further less significant increase at mature stages. Between colostrum and transitional stages, phosphorus concentration showed a significant increase $(9.9pm2.4$ vs $15.5pm4.9$ mg/100 ml, p<0.001)but between the 25-35 day and the 55-70 day stage phosphorus values did not change significantly. Ca/P ratios for colostrum. transitional, the 25-35 day and the 55-70 day stages were 2.28, 1.76, 1.68 and 1.95, respectively. No significant relationship was found between ash. calcium, phosphorus or Ca/P ratio of milk and maternal parity. When modified milk formulas were reconstituted using the total solids of human mature milk as amount of the modified milk formula in 100 ml of infant feeding solution. ash, and Ca/P ratio were similar to those of human milk. However considerably higher concentrations of calcium and phosphorus exist in the reconstitution fluid than those observed in human milk.