Abstract: Interpreting student errors have little been accorded full-scale treatment. The objective of the article is, then, to provide a classification of and explain some of the most recurrent grammatical errors made by students in Russian-to-English consecutive interpreting. Our findings suggest that all grammatical errors in student consecutive interpreting fall into four groups: errors in the use of articles; errors in the use of tenses; errors in the use of voice; and errors in the use of number. Among the key sources of grammatical errors in consecutive interpreting are inadequate linguistic competence and performance, i.e. tendency to transfer grammatical patterns specific to a native language into a foreign language, unpredictable syntax, quick speech motor actions; and psychological and cognitive factors, i.e. principles of analogy, severe time constraints. Error analysis in student consecutive interpreting can make a positive contribution into the practice of training interpreters as it reveals the problem triggers. Additionally, inquiries in error analysis can make valuable contributions in a linguistic typology of interpreting errors in typologically and structurally different languages, i.e. language-specific and language-pair specific errors.