In Conn's syndrome, adrenal vein sampling (AVS) is used to secure the site of hormonal overproduction. The left adrenal vein is usually easy to explore, the right is difficult. Examination requires several differently configured catheters. Here, we introduce a new technique for AVS using a single cobra catheter, which was tested in n = 13 patients. In an inverted configuration, the cobra catheter can be used to explore the left side, while the regular configuration can be used for the right side. The technical details are described in the manuscript. In all patients, left AVS could be performed successfully using the inverted catheter configuration. In n = 11 patients, right AVS was carried out successfully with a cobra catheter in regular configuration. In two cases, a Sidewinder-I catheter was required due to a steep angle of the adrenal vein.