Background and Objective: Adulteration of dairy products by substitution of milk fat by vegetable oil is common in the Eurasian Economic Union. The objective of the paper is to investigate the potential adulteration of the fat and to test the more convenient methods of detection, i.e., determination of fatty acids or sterols profiles in commercial butter and cream. Materials and Methods: Ten samples of commercial butter and 8 samples of commercial sour cream were collected on the national market of Kazakhstan. The analyses involved the original sour cream and butter without any modification (deep-freezing) and were achieved within the shelf-life period. The fatty acid composition was analyzed by GS-FID and Sterol fractions were analyzed by GS-MS. Statistical analysis was achieved by principal components analysis (PCA), Pearson types, Kruskal-Wallis test. Results: Sixty percent of the butter samples contained traces of phytosterols and one sample contained up to 78% $-sitosterol. In sour cream samples, only three contained 100% cholesterol while two contained more than 60% sitosterol. The detection of fat adulteration by analyzing the fatty acids patterns is convenient in case of massive substitution of milk fat, but a discrete substitution does not modify the fatty acids profiles leading to misinterpretation. Conclusion: The results exhort to give preference to sterol profile determination as an official method to detect fat adulteration in dairy products. This is even more important as the current standard used in Central Asia based on some fatty acids ratios can lead to incorrect conclusions.