The Virginia Department of Forensic Science (DFS) receives tens of thousands of drug samples every year, submitted by law enforcement agencies across the state. Drug categories listed here include both illicit and other substances that were seized and tested. Note that some drugs may not be illegal to possess, if the individual has a valid prescription. It is impossible to identify the existence or validity of a prescription in the DFS data.

Drug submission data were provided by DFS, using information collected for the National Forensic Laboratory Information System. In 2021 the DFS chemistry team wanted to make adjustments to how some individual drugs were categorized, and therefore, data from this site will slightly differ from the current DFS drug data report. For example, "Club Drugs" has been broken into two groups, Hallucinogens and Designer Drugs in the DFS report. DFS also broke out the benzodiazepine data into illicit vs prescription versions and this change will not be reflected here.

When multiple drug samples of the same type of drug were submitted as part of the same case, they were only counted a single time, as one case. When multiple samples of different drug types were submitted as part of the same case, they were counted as a single case for each drug type included.

The locality listed in the table is the jurisdiction identified in the DFS data. Fewer than 1% of cases have a jurisdiction that did not match a locality (e.g., U.S. Dept. of Forestry), and are not counted. In some cases, drugs seized in one locality may be sent to DFS via another locality. This appears to be common for the cities of Manassas and Manassas Park cases for which are usually identified as being from Prince William County. It may occur with less frequency in other jurisdictions.