Laurie Dulle mentioned a baby that was keeping formula down, but vomiting when he received breastmilk. My one year old was doing the same thing. On days that I couldn't pump enough to bring to the daycare the following day, the daycare staff would supplement him with a bottle of formula. When I would feed him at home that evening, he would always vomit up all of the breastmilk. I just assumed it was just a delayed allergic reaction to the formula so I switched him to a soy-based formula and we haven't had the problem since then. My supply seems to be back up now so he hasn't needed any formula for a few weeks now, but for a while he was getting three or four bottles a week. As soon as we switched to the soy formula, the vomiting stopped. Donna J. Spannaus-Martin, Ph.D., MT (ASCP) Assistant Professor, Clinical Laboratory Sciences http://www.utmem.edu/allied/Med.Tech./med.tech.html University of Tennessee, Memphis