The adrenal glands are small endocrine organs located on the bottom pole of each kidney. Anatomically they are composed of cortical and medullar parts. Due to dysfunctional processes they can transform into the pathological lesions (in both cortex and medulla). The incidentally detected adrenal lesions have become an arising clinical problem nowadays. The crucial issue for an accurate treatment strategy is relevant diagnosis. Distinguishing between benign and malignant lesions is often difficult during the standard histological examination. Hence the alternative methods of differentiation are investigated. One of them is Fourier transform infrared spectroscopy which allows the analysis of the biomolecular composition of the studied tissue. In this paper we present the very preliminary FTIR studies for defining the biomolecular pattern of three types of adrenal lesions: adenoma (AA) and adrenal cortical hyperplasia (ACH) - both derived from adrenal cortex as well as pheochromocytoma (PCC) - from the medullar part of the gland. All studied cases were classified as benign lesions. The general observations show that cortically derived tissues are rich in lipids and they are rather protein depleted while for medullar pheochromocytoma there is the opposite relationship. Furthermore, the unequivocal differences were noticed within the "fingerprinting" range. In addition subtle shifts in absorption band positions were observed between studied cases.