LSM-775, also known as N-morpholinyllysergamide or as lysergic acid morpholide, is a psychedelic drug of the lysergamide family related to lysergic acid diethylamide (LSD).

LSM-775 is less potent than LSD but is reported to have some LSD-like effects at doses ranging from 75 to 700 μg and a shorter duration. It may only produce weak or threshold psychedelic effects in humans. There are claimed to be fewer signs of cardiovascular stimulation and peripheral toxicity with LSM-775 compared to LSD.^{[dubious – discuss]}

LSM-775 is a potent full agonist of the serotonin 5-HT_1A receptor and a potent partial agonist of the serotonin 5-HT_2A, 5-HT_2B, and 5-HT_2C receptors. It does not produce the head-twitch response, a behavioral proxy of psychedelic effects, in rodents. However, LSM-775 can robustly increase head twitches if it is coadministered with the serotonin 5-HT_1A receptor antagonist WAY-100635. These findings indicate that serotonin 5-HT_1A receptor activation suppresses the psychedelic-like effects of LSM-775.

LSM-775 was first described in the scientific literature by Albert Hofmann and colleagues by 1955.