The classical hallucinogens having an affinity towards 5HT2A receptors are discussed, along with their common behavioral effects, toxicity and psychiatric complications which could have long-Term consequences on individuals. A survey has been done on the various analytical methods used for determination and quantification of hallucinogens: colorimetrical reactions (Marquis, Ehrlich tests), gas chromatography with mass spectrometry (when the substances are not thermo labile), tandem mass spectrometry, high-performance liquid chromatography with UV detection and JR spectroscopy. Methods most often used to analyze biological samples like urine, blood or plasma immunological methods for quick detection, which results are confirmed later by the other methods mentioned above have been also discussed.