Abstract: The purpose of this study was to explore the patient’s belief on the causes of mental illness in Nigeria. An exploratory- descriptive design within the qualitative paradigm was used. In-depth one-on-one interview with thirteen (13) participants between the ages of 30-54 years old. All participants consented to participate and they were used purposively sampled. No form of coercion was used to attract or retain them. The interviews were audio taped and transcribed verbatim after which content analysis was done to identify themes and categories. A key finding in this study was that patient’s belief on the causes of mental illness indicated that patients believed Thoughts/thinking, feelings, and emotions as the causes of their illness. Other findings included: witchcraft, emotional experience, resources, occupations, and family/homes. It was recommended that health care providers should create an avenue to enlighten their patients on mental illness.