Phosphodiesterases (PDEs) are enzymes that play a role in the regulation of the second messenger molecules, cAMP and cGMP. PDE enzymes are classified into 11 families, PDE1 to PDE11. Due to their physiological effects, PDE inhibitors have been identified as new potential therapeutics in areas such as pulmonary arterial hypertension, coronary heart disease, respiratory disease, metabolic disorders, dementia and more recently in some forms of depression. Here, we implicate PDE11 in the aetiology of schizophrenia. PDE11 expression is detected in the brain in small amounts and has been linked to the treatment of diseases or conditions that affect the prostate, reproduction and more recently major depressive disorder. We have identified a number of compounds with low to sub micromolar IC50 activity against PDE11A1. We have identified Compound A, which indicates an IC50 value of 300nM and shows selectivity of greater than 300 against all other PDE families. This compound has also been tested in a murine model of Pre Pulse Inhibition (PPI) an in vivo model of schizophrenia. Compound A indicates efficacy in this model at a dose of 50mg/kg and at a dose of 15mg/kg, when PCP is incorporated into the PPI model. The compound has no effect in open field activity models. This study indicates a potential role for the PDE11 family in the treatment of Schizophrenia.