a b s t r a c tA comparison between Muḥammad and Siddh artha's psychological states is made to identify how they had their mystical experiences and how their presuppositions and personalities shaped their interpretation of these experiences. Muḥammad's mystical experience appeared to be based on an altered state of consciousness. Siddh artha's teachings include that one must not have blind faith and remain open to various truths. These teachings may reflect that he was high in openness to experience, which may have fortified him from becoming delusional. While mystical experiences may have pathological overlaps, they could be categorized in a similar way to psychological states. Yet, mindful presuppositions and personality traits, especially from within openness to experience spectrum, are what make perceptions of these experiences diverse. k e y w o r d s : Buddhism, Islam, mystical experience, personality, psychology & i n t r o d u c t i o nThis article looks into the descriptions of mystical experience by Muḥammad, according to Muslim tradition, when he first described receiving divine revelations and compares it with the experience of Siddh artha, also known as the Buddha, according to the P ali canon. A comparison of these experiences may suggest that they have a similar neuropsychological basis but that the individual's presuppositions and personality cause a difference in the interpretation of these experiences.