Adrenocortical carcinoma (ACC) is a malignant tumor, which can occur at any age. The prevalence of ACC in population is 0.5-2 cases per 1,000,000 people per year; the incidence of ACC in patients with adrenal incidentalomasis 1.2- 12%. By the revealing adrenal tumor, it is necessary to identify whether this adrenal mass is malignant or/and hormonally active. In spite of using such visual diagnostic methods as ultrasound, CT, MRI, PET, it’s not always possible to detect malignancy of adrenal mass in daily clinical practice. Some experts suppose that urinary steroid profiling (USP) is the most significant for the diagnosis of adrenal carcinoma. The researchers note an increase of adrenal steroidogenesis precursors in 85% of patients with ACCby gaschromatographymass-spectrometry (GC-MS) and consider it is more sensitive and specific for differential diagnosis between benign and malignant adrenocortical tumors. In our study we determined steroid profiling in combination of HPLC and GC-MS data. Urinary steroid profiling (USP) were studied by methods of high-performance liquid chromatography (HPLC) and gas chromatography-mass-spectrometry (GC-MS) in 139 patients with adrenocorticaladenoma(ACA) and 31 patients with adrenocorticalcancer(ACC). The main features of ACC were increased levels of the following urinary steroid metabolities:tetrahydro-11-deoxycortisol (THS), dehydroepiandrosterone (DHEA)and its metabolites, etiocholanolone, 16-oxo-androstendiol, pregnanediol, pregnanetriol (P3), 11-oxo-P3, 6β-OH-pregnanolone, pregnenediol (dP2), 3α,17,20-pregnenetriol (3αdP3), 3βdP3,3α,16,20dP3, 3β,16,20dP3, 16-OH-pregnenolone (16dP), 21dP, 21dP2and11dP3, also 11β-hydroxylase and/or 21-hydroxylase deficiency. However, DHEA was increased in 67.7% of patients with ACC and THS - in 74.2%. The highest sensitivity and specificity for the differential diagnosis of ACC and ACA were achieved by combination of following parameters: THS> 900 µg/24 hr and/or DHEA> 1500 µg/24 hr with relations of 3α,16, 20dP3 / 3β,16,20dP3 less than 6.0 and 3αdP3 / 3βdP3 less than 9.0, and the detection of at least 2 of 5-en-pregnens not revealed in patients with ACA.The findings show the importance of using GC-MS and HPLC for differential diagnostics of ACC and ACA, which in combination with imaging could improve the accuracy of diagnosing ACC before surgery. The further studies are needed for finding the most informative biochemical markers of ACC.