Parssinen has published Secret Passions, Secret Remedies: Narcotic Drugs and British Society, 1820-1930,and Webs of Smoke: Smugglers, Warlords, Spies and the History of the International Drug Trade. Using memoirs and recently discovered documents, Parssinen has published the first-ever book on the little-known plot that collapsed following the Munich conference of 1938: The Oster Conspiracy of 1938: The Unknown Story of the Military Plot to Kill Hitler and Avert World War II.
In a deposition taken for Sulcer v. R.J. Reynolds in September 2010 Parssinen declared that he charged $135 an hour for his research on tobacco-related issues. He furthermore stated that he had made around $360,000 with litigation-driven work for the tobacco companies. One year later, in a deposition pertaining to McCray v. R.J. Reynolds Parssinen disclosed he had made $450,000 as an expert judicial witness for the tobacco industry. The following year Parssinen acknowledged in an expert report submitted in Rodehaver v. R.J. Reynolds that his hourly rate for research was $135, and that for testimony $200.
 See deposition of Terry Parssinen, September 8, 2010, Sulcer v. R.J. Reynolds. Westlaw reference: 2010 WL 9926701.
 See deposition of Terry Parssinen, September 26, 2011, McCray v. R.J. Reynolds. Westlaw reference: 2011 WL 8741848.
 See expert report of Terry Parssinen, June 21, 2012, Rodehaver v. R.J. Reynolds. Westlaw reference: 2012 WL 3541162.