Use of both cannabis and synthetic cannabinoids has been regularly linked to the development of psychotic illness. Thus, semisynthetic cannabinoids such as hexahydrocannabinol (HHC), which have a similar neurobiological profile to delta-9-THC, may also be expected to lead to psychotic illness. However, no such relationship has yet been reported in scientific literature. HHC is readily available online and in many vape shops in Ireland. Here, we present two cases of psychotic illness which appear to have been precipitated by use of legally purchased HHC and discuss its psychotogenic role and factors linked to its current widespread availability.