The article is devoted to the problem of compliance with lexical-semantic (lexical) norms of the modern Ukrainian literary language in the speech of higher education students as an important component of their professional competence and speech culture.The purpose of the work is to identify, describe and systematize lexical and semantic norms, to clarify their causes in the aspect of the problem of speech culture in order to organize effective work on their elimination.The article uses a descriptive method, methods of functional-semantic and contextual analysis.The work defines the concepts of “language culture” and “speech culture”, emphasizes the differences in their definitions, identifies the communicative features of speech culture, and reveals the meaning of the terms “language norm”, “literary language norm”, and “lexico-semantic norm”. It has been found that such communicative features of speech culture as accuracy, correctness, richness of speech, purity, appropriateness, etc. are directly related to perfect mastery of the vocabulary of the language, adherence to the lexical and semantic norms of the literary language.Based on observation of students’ oral and written speech, the most common lexical errors were identified: using of mixed language (surzhyk) elements, Russianisms, copied constructions, indistinguishability and confusion of the meanings of paronymous words and the meanings of interlingual homonyms, stylistically unjustified using of pleonasm and tautology, excessive using of foreign words, in particular Anglicisms, using of dialectisms, parasitic words, invective vocabulary, etc.Objective and subjective reasons that cause lexical and semantic errors are formulated: convergence, interference of languages; significant influence of the sociocultural and dialectal environment of speakers on their level of speech culture; a significant array of vocabulary, which is difficult to master at the proper level; the impossibility of reducing lexical norms to a limited number of clearly formulated rules; mobility, dynamism of the lexical composition; insufficient awareness of students with the lexical norms of the modern Ukrainian literary language, the lexical richness of the language, limited vocabulary, and a general low or insufficient level of speech culture.