Growth factors enhance tensile strength, angiogenesis and collagen synthesis in skin wounds. The effects were studied of a continuous intraperitoneal infusion of epidermal growth factor (EGF) on the mechanical properties of healing in linear full-thickness wounds of the stomach, ileum and colon of young pigs (n = 16, mean(s.d.) body-weight 20.1(1.9)kg). In half the animals an osmotic minipump was implanted into the peritoneal cavity to deliver recombinant human EGF at a rate of 0.5 micrograms kg-1 24 h-1. Animals were killed at 5 days and the integrity of a 20-mm ring of intestine was tested for tensile strength. Breaking strength (g mm-2) of the intestinal wounds in untreated pigs (n = 8) was: stomach 28.0(2.0), ileum 46.8(4.8), colon 85.6(4.2). Intestinal wounds in pigs (n = 8) receiving supplemental EGF had significantly increased breaking strength: stomach 32.4(2.2) (P less than 0.05), ileum 56.8(5.4) (P less than 0.05), colon 96.0(3.8) (P less than 0.01) compared with untreated animals. At 5 days after the initial injury intraperitoneal EGF increases the tensile strength of intestinal wounds in pigs.