The article is devoted to the description of the idiomatic potential of Russian colloquial speech, revealed on a voluminous corpus material. The observations and conclusions are based on the analysis of the material of two oral corps: Russian everyday speech (“One speech day”, mainly dialogues and polylogies of native speakers) and Russian monologue speech (“Balanced annotated text collection”). Both corps were created at St. Petersburg State University and allow multilevel analysis of both types of oral speech. In a broad sense, all the units that refer to idioms meet the criteria of stability, reproducibility, and also the integrity of the value of a unit, which cannot be reduced to the sum of the values of its components. As the analysis of the corpus material has shown, our speech is rich in such idioms: the maximum number of idioms per fragment of the record is 1.1 % (the average share is 0.2-0.3 %). For a minute of communication, the speaker (along with his interlocutors) is able to use up to 2 idioms. The article presents the results of the analysis of everyday Russian speech. The main array of idiomatics is not only the units recorded in dictionaries, but also colloquial neoplasms and everything that can be called the idiomatic potential of colloquial speech. A certain systematization of this potential is proposed in the article: (1) modifications (s polotencem napereves); (2) contamination (ni v koej zhizni); (3) occasional formations (golovu zakhlaml'at' negativami); (4) generalized statements understandable to native speakers, but requiring comments in a foreign-language audience (kak razd l'ablondinok); (5) precedent texts, often modified (ikh jest'u men'a); (6) speech formulas, or grammatical constructions-collocations (Pravda chto li?! pon'al net?); (7) prepositional-case combinations (forms-idioms) (bez nikakix). The criterion of idiomaticity in most cases can be the possibility of replacing a speech fragment with a unit-identifier.