Cannabis use is now more frequent than alcohol drinking or tobacco smoking among young people (15-34years), whereas it may induce numerous medical aftermaths. Identifying and assessing cannabis use in general practice have become a current public health issue. The two steps of screening consist in spotting risky use of cannabis, and then in checking criteria for cannabis use disorder (CUD). Risky use requires a "brief intervention" by the general practitioner (GP). In case of CUD, the new DSM-5 criteria allow measuring the severity of the subsequent disorder, and listing the medical and social consequences. Using these criteria can help the GP to decide when the patient should be referred to an addiction-specialized unit. The GP has also to spot the different physical and psychiatric complications of cannabis use, in order to coordinate care between the different specialists.