On the Simulation (i.e. Faking) of Mental Disorders (original German: Über Simulation von Geistesstörung) is an early 1903 essay by Jung on the challenges of diagnosing mental conditions when the patient is confused themselves. Jung addresses the intentional feigning or simulation of mental disorders. He examines the challenges of differentiating between genuine mental illness and simulation, particularly in legal and clinical settings. Jung notes that while many simulators are not mentally normal, they often have traits of degeneracy or hysteria. These traits can complicate the diagnosis, as hysterical individuals may exhibit behaviors that mimic genuine mental disorders. The document highlights the challenges faced by psychiatrists in differentiating between real and feigned symptoms, stressing the lack of an infallible method to unmask simulators.

This edition contains a new 2023 translation from the original German manuscript with an Afterword by the Translator, a philosophic index of Jung's terminology and a timeline of his life and works.