Abstract: Orally or rectally administrable formulations of biologically active material comprise a water-in-oil microemulsion, wherein the hydrophilic phase of the microemulsion comprises the biologically active material and the hydrophobic phase comprises chylomicra or material capable of forming chylomicra in the intestinal mucosa after administration. The biologically active material may be any of a wide range of substances including insulin, calcitonin and somatotrophin or growth hormone. Formulations of the invention are particularly suitable for the oral administration of insulin in the treatment of diabetes.