The longitudinal changes on human milk volume per day and lactational performance of 23 Korean lacto-ovo-vegetarians(primiparae=11, multiparae=12) from 0.5 to 5 months after parturition have been studied by test weighing method. The human milk volume per day tended to increase during lactation. The mean volume (SD, ml/day) at 0.5, 1, 2, 3, 4, 5 months were 502(102), 692(127), 697(100), 684( 125), 757(52), 703(70), respectively. The overall mean volume was 661$pm$132ml/day. The peak milk volume during the lactation was observed at most lactating women at the 1st month. The distributions of the individual mean volume during the first 5 months of lactation were found over 750m1(8.7% ), 650-750ml(47.9% ), 550-650m1(2l.7% ), and 450-550ml(2l.7% ) The number of feeding per day was 8.1 ($pm$1.0) at 0.5 months postpartum, which was consistently decreased. However, the mean volume per feeding was increased from 62($pm$9.5)ml at 0.5 month to 112($pm$13.3)ml at 5 months postpartum. The milk volume was correlated with the peak volume. and maternal age. but not with weight before delivery. maternal height and birth weight. No differences of milk volume and lactational performance between facto-ovo-vegetarian and nonvegetarian women were observed. This study suggests that the human milk volume cited in the recommended dietary allowances for Koreitns is over estimated.