Bilaid A (FvVf-OH) is the major analogue of a family of tetrapeptides with an unusual alternating LDLD chirality isolated from an Australian estuarine isolate of Penicillium sp. MST-MF667. Bilaid A is a weak μ-​opioid agonist and the class formed the foundation for the design of more potent analogues, bilorphin and bilactorphin. The role of the bilaids in the fungus’s secondary metabolite cohort is unknown.