Pelvic adhesion formation represents a major problem following fallopian tube surgery for infertility. Intraperitoneal dextran may prevent pelvic adhesions. Extensive personal clinical experience (W. H. U.) with intraperitoneal dextran organ-flotation on completion of tubal and ovarian surgery has appeared to limit adhesions. A specific study was designed to test the validity of this theory. Four randomized groups of rabbits were subjected to bilateral tubocornual division and microsurgical reanastomosis with total hemostasis and pelvic lavage. Routine peritoneal closure was performed on one group, but followed instillation of 30 to 50 ml of normal saline into the peritoneal cavities of the second group, and 30 to 50 ml of 6% dextran 70 into those of the third. Study of fourth group, which received 32% dextran 70 in the peritoneal cavity, was discontinued because of complications. A second laparotomy was performed 4 weeks later for precise assessment and photography of adhesion formation. Each animal was mated 4 weeks after the second operation in order to determine fertility rates. Reduced adhesion formation and increased fertility rates following the instillation of dextran are reported. A role for dextran 70 in infertility surgery is recommended.