Evidence from the peritoneal dialysis literature suggests that the peritoneal permeability of a number of hydrophilic anticancer drugs may be considerably less than plasma clearance. Pharmacokinetic calculations indicate that such drugs administered ip in large volumes are expected to maintain a significantly greater concentration in the peritoneal space than in the plasma. This concentration difference offers a potentially exploitable biochemical advantage in the treatment of patients with presumed microscopic residual ovarian cancer confined to the peritoneal cavity.