In modern studies of language, the focus of attention is on the functional features of linguistic phenomena. Functional grammar is no exception, describing the structure, content and functioning of semantic categories around which functional-semantic fields are organised, covering the whole language space and its different levels (aspectuality, modality, quantity, quality, etc.). This study considers condition as a subfield of the conditionality field, which also includes the subfields of cause, purpose, consequence and concession, which are closely related to each other both by internal logical relations and by means of their expression. Despite a number of studies devoted to the structure of the conditionality subfield and its separate manifestations, including conditional constructions, conjunctions and prepositions, the issues of discourse variability of the components of this subfield have not been specifically considered. Conditional relations seem to be most significant for scientific discourse, on the material of which this study is based. The scientific literature describes the conditional meanings characteristic of the corresponding constructions and constituting the content plan of the condition subfield. These are real-conditional, potential-conditional, unreal-conditional, as well as non-conditional meanings – conditional-temporal meaning, conditional-causal, conditional-consequential, conditional-purpose, conditional-concessive, conditional-explanatory. Thus, the conditional semantics is in the intersection with related meanings (including conditionality), is extremely diverse, as well as diverse means of its expression - at the level of simple (to be a condition, to condition, at, under condition, in the case of, etc.) and complex (with conjunctions if, if, if only, when, etc.) sentences. This study is based on the assumption that the means of expressing conditional semantics vary in different thematic types of scientific discourse. Turning to the core genre of scientific discourse – the scientific article – confirms this assumption. The material of the study was 3 708 articles from the peer-reviewed journals “The World of Russian Word” and “Bulletin of Tomsk State University”. In the course of the analysis, more than 60 000 contexts with conditional meanings, collected by the method of continuous sampling, from articles on philology, history, biology, computer science and informatics, and economics were considered. The analysis showed that not all private meanings of conditionality presented in the language are manifested in scientific discourse. When expressing conditional relations in the articles of the five mentioned subjects, the central position is occupied by simple sentences with the preposition at, at the level of a complex sentence the marker of conditional semantics is the conjunction if. The qualitative and quantitative indicators with regard to conditional constructions for articles of different themes differ significantly. Thus, the study shows the variability of the expression plan and content plan of the conditional subfield, the differences in the use of conditional units in different types of scientific discourse.