Currently international accounting for business combinations is considered to be the one of the predominant features of the 21st century economy. In response to such current challenges the aim of the paper consists in an attempt to introduce the fundamentals of US GAAP and IAS/IFRS accounting for business combinations and perform their qualitative comparison. The applied methodology is based on multidisciplinary approach designed for accounting for business combinations. The conducted research indicates that for today the accounting amounts reported under US GAAP and IAS/IFRS in context of accounting for business combinations are considered to be highly relevant and comparable. Generally under both sets of Standards accounting for business combinations is realized in a sequence of four steps: first an acquirer and acquisition date are determined, then acquired assets and assumed liabilities are recognized and measured at fair value, after that a set of consolidated financial statements for combining entities is compiled, and, finally, goodwill or bargain purchase is identified and impaired. Although significant harmonization and unification have been reached in this field still some differences in accounting policies continue to remain. As the most disordered and debated topics there are considered to be accounting for goodwill, fair value measurement of non-controlling interests and impairment of intangible assets.