This article analyses an aggregation of criminal offences as one of types of multiplicity of criminal offences and the problems of its qualification. The issue is topical from both theoretical and practical point of view, since the process of applying legal norms is often associated with difficulties in determining whether a separate (unitary) criminal offence has been committed, or a multiplicity of criminal offences is to be established; errors are made in distinguishing a factual aggregation of criminal offences from the legal institute, such as collision of legal norms. By emphasising different elements of the said legal institutes, recommendations correspondent to practice needs, which are based on the legal framework, conclusions of the theory of criminal law and of case-law, as well as analysis of practice are offered. Particular attention is paid to compound criminal offences, the structure of which includes serious consequences, reference to the application of violence or inflicted bodily injuries, and in the process of qualification of which one has to encounter the formation of a conceptual aggregation, which is related to serious problems in practice. Likewise, the authors establish that the legislator, in designing the norms of the Special Part of the Criminal Law, has failed to observe all the conditions of development thereof. Thus, a conceptual aggregation of criminal offences, which, in our opinion, should be an exception in cases of compound criminal offences, becomes a regularity authorised by the legislator. Likewise, the article provides a reasoned opinion on the qualification solution in the event if one criminal offence is a way (tool, method) by which another criminal offence is committed, as well as on the formation of an aggregation of criminal offence stipulated by CL Sections 177 and 178 implemented in practice, thus violating provisions of collision of general and special norms included in CL Section 26 Paragraph five.