Background. From a linguistic point of view, medical texts are interesting primarily as a material for studying medical terminology, which is the subject of many scientific papers, including in the field of historical terminology. This article substantiates that the commonly used vocabulary of historical medical texts has its own characteristics and is of scientific interest. The object of the research is the development of non-terminological vocabulary of the Russian literary language of the first half of the 19th century based on scientific medical texts. The purpose of the work is to analyze the commonly used vocabulary of historical texts in lexicographic, lexico-semantic, and word-formation aspects. Materials and methods.The research material was the scientific medical texts of the 19th century on pharmacology by Alexander P.Nelyubin(1785-1858) and Pyotr F.Goryaninov(1796-1865) – professors of the Imperial St. Petersburg Medical-Surgical Academy – the highest specialized educational institution of the Russian Empire. The comparative-historical method, which was used when working with the material of the 19th century,contributed to achieving the goal of the work, as well as removing possible linguistic difficulties when reading specific historical texts by a modern reader. Results.A comparative analysis of non-terminological words was carried out from two sides: for compliance with the literary norms of the nineteenth century and in comparison with the norms of the modern Russian literary language. The result of the work showed that in scientific medical pre-revolutionary texts there are spellings of words that do not comply with the spelling rules of the nineteenth century, the inconsistencies identified are few. The study revealed the following deviations from the orthographic norms of the 19th century:spelling of the words "doctor", "medicine", "professor", "surgeon", "phytologist" with a lowercase letter; spelling of the word "ether" with the letter "f"; spelling of the prefixes raz-, iz-, voz- with the letter "z" in words where a voiceless consonant is written after the prefix, except for the letter "s"; double spelling of words. Spelling that differs from the standard is explained by several reasons: the process of democratization of the language of the 19th century, the existence of two equal spelling variants, author's errors, and typos when typesetting texts in a printing house. The analysis of lexical and semantic features of non-terminological words in scientific medical texts has shown that changes in the lexical meaning and stylistic affiliation of words reflect the general process of democratization of the Russian literary language of the 19th century, which manifested itself in the reduction of Church Slavonic vocabulary and loanwords and the inclusion of dialectal, vernacular and colloquial elements in its composition.