Abstract: The VIth International Symposium “The Chemistry of Diazo Compounds and Related Systems” (DIAZO 2021) was held at the St. Petersburg State University from 6 to 10 September 2021. At the symposium, the advances in diazo chemistry over the past decade were summed up, and promising directions for further research were discussed. The review contains brief annotations of the plenary, keynote, invited and oral presentations and includes references to the relevant works of the speakers.