Psychedelics derived from lysergic acid diethylamide (LSD) represent one of the groups of new psychoactive substances (NPS) that have been gaining popularity in recent years. Due to their very high potency, they are taken in small doses and their identification in biological material is problematic. The compounds from this group, which appear in low concentrations in biological material and metabolise rapidly, require sensitive and selective analytical methods if they are to be detected. A method for the detection and determination of LSD and its new derivatives (ALD-52, 1P-LSD, 1cP-LSD, and 1B-LSD) in whole blood using the LC-MS/MS technique was therefore developed and validated. The analytes were isolated from the blood (0.2 mL) by liquid-liquid extraction with ethyl acetate and acetate buffer (pH 5.5). The method developed was linear in the range of 0.5−10 ng/mL. The limit of detection (LOD) was 0.01 ng/mL for each analyte and the lowest point on the calibration curve was taken as the limit of quantification (LOQ). The method developed is sensitive and samples can be prepared for analysis quickly and easily. The procedure can be applied widely in the analysis of LSD derivatives in biological material –for forensic or clinical purposes, for example –and can easily be expanded for use with further LSD derivatives.