Being the most available illicit substance all around the world, growing evidence is pointing out that cannabis use carries an increased risk for the development of mental disorders. Although cannabis is abused for its euphoric effects, it may also cause depersonalization, psychosis, panic attacks and mood disorders. Such clinical conditions are usually acute, transient but persisting or recurring symptoms with continued use of cannabis are documented as well. In this case report, an individual who developed schizophrenia after a single use of cannabis, is described. A 36-year-old single male pilot was fetched to our psychiatry outpatient service by his friends with the complaints of disorganised speech and behaviors, paranoid and mystic identity delusions starting a week ago. His vital signs were normal and physical examination was unremarkable. Results of extensive blood work, including complete blood count, electrolytes, as well as hepatic and renal function tests were normal. Urinal toxicological analysis was negative for cannabis. His medical history and family history revealed nothing significant. He believed that he had a special mission given by the prophet and was being chased by some people he did not know. He was started on olanzapine 20mg/day and discharged after twelve days. After the resolution of symptoms he told that he had a single dose of cannabis mixed with tobacco, a week before his admittance. During the first three months he visited for follow-up regularly, but he discontinued the medication after then. Six months later, he was rehospitalized with delusions and agitation. After 20 days, he was discharged and due to metabolic side effects of prior treatment, aripiprazole 15mg/day was prescribed. With a gradual improvement, aripiprazole was tapered down to 5mg/day by the end of first year. He is still free of psychotic symptoms and working as a şight instructor. In animal studies, cannabis enhances dopaminergic neurotransmission in brain regions known to be implicated in psychosis. Studies also show that genetic vulnerability might add to increased risk of developing psychosis. In this case report, we would like to show that a single dose of cannabis can precipitate schizophrenia.