Paraneoplasic hypercorticism results from ectopic corticolipotropic secretion. Its incidence remains underestimated because of the latent clinical forms of Cushing's disease. In some cases the primary tumour (bronchopulmonary, thymic, pancreatic or other) presents late. The variability of hormonal secretion makes it difficult to interpret dynamic tests. Measurement of ACTH and LPH are useful diagnostic aids; more specific markers of ectopic secretion have recently been reported. When the primary tumour cannot be directly treated, the quality of survival may be improved by the use of synthetic anticortisol drugs.