For the ras oncogenes analysed, exon 1 to exon 2 of H-ras and K-ras genes in the tumour tissues of 13 Conn's syndrome, two adrenal Cushing's syndrome, two non-functional adrenal tumours, one adrenocortical hyperplasia and eight phaeochromocytomas and its paired adjacent normal adrenal tissues were amplified and sequenced. This evidence concerns the gene KRAS and pheochromocytoma.