The composition of cannabis products (herb, resin, oil), whose active ingredient is delta-9-tetrahydrocannabinol (THC), is a subject of debate in France and across Europe. Until now, the only data available in France came from analyses of products seized by law enforcement agencies. Drawing on its experience in collecting ecstasy samples from users, the French Monitoring Center for Drugs and Drug Addiction (OFDT) conducted an experimental collection of cannabis samples from consumers, who were generally in possession of products that had not undergone further processing. (R.A.)