Cannabis use is growing in the Irish population. Generally users and nonusers alike are unaware as to the full potential of the possible negative consequences from cannabis use. This paper aims to investigate these negative consequences, and compare them to the possible positive (medicinal) uses of the drug. This paper presents a literature review of the research, investigations and studies relating to cannabis use. A review of the present literature has found that cannabis is undoubtedly more of a harmful substance and should be presented this way by psychologists and medical professionals alike. However, this paper has highlighted some ambiguous and conflicting reports and so more research in this area is recommended to gain a full and frank picture of cannabis use.