Amphetamines, tryptamines, phencyclidines, tetrahydrocannabinol and substances of the ecstasy group are characterized as stimulants, hallucinogens and entactogens. The various effects of each group and their mode of action in different transmitter systems are described. 28 new compounds of the amphetamine and tryptamine series has been calculated, which exceed the hallucinogenic effects of mescaline. The different pathways of the metabolism of MDMA (ecstasy) and MDE in humans may probably explain their individual effects.