Abstract Street samples of heroin (n = 102) and amphetamine (n = 120) seized in different areas of Denmark during a one-year period were analyzed for purity and additive content. The mean concentrations of the heroin and the amphetamine samples were 34 and 35%, respectively, but the purity of both drugs varied greatly. Sugars and caffeine were the most frequently encountered cutting agents in both drugs. The additives phenobarbital, methaqualone, and procaine were seen only in heroin, especially in heroin base. Half of the heroin samples were heroin base, the other half heroin chloride. Brownish samples of heroin base containing large amounts of opium alkaloids dominated in the seizures in the provincial towns, whereas white/beige samples containing heroin chloride with little or no papaverine or noscapine were frequently seen among the seizures in the capital. The result may indicate different import routes for heroin to the eastern and western parts of Denmark.