4-HO-PiPT, also known as 4-hydroxy-N-propyl-N-isopropyltryptamine or as piprocin, is a substituted tryptamine derivative which is claimed to have psychedelic effects. It has been encountered as a novel designer drug.

4-HO-EPT was not included or mentioned in Alexander Shulgin's book TiHKAL (Tryptamines I Have Known and Loved).

4-HO-PiPT acts as a serotonin 5-HT_2A receptor agonist, with an EC₅₀Tooltip half-maximal effective concentration of 13.8 nM and an efficacy of 104.8%.

Analogues of 4-HO-PiPT include propylisopropyltryptamine (PiPT), 5-MeO-PiPT, 4-HO-MiPT, 4-HO-EiPT, 4-HO-EiBT, 4-HO-DiPT, 4-HO-DsBT, 4-HO-McPT, and 4-HO-McPeT, among others.

4-HO-PiPT has been sold as a designer drug, first being identified in 2021 in British Columbia, Canada.