The present invention provides triazolopyrazinones as PDE1 inhibitors and their use as a medicament, in particular for the treatment of neurodegenerative disorders and psychiatric disorders.La presente invención proporciona triazolopirazinonas como inhibidores de PDE1 y su uso como un medicamento, en particular para el tratamiento de trastornos neurodegenerativos y trastornos psiquiátricos.