The mental and physical capabilities of drivers in traffic are often seriously challenged these days. Not only do they need to concentrate on driving, predict connections between various phenomena, take appropriate judgements in current situations and foresee the sequence of measures to be taken, but they are also expected to be emotionally stable, etc. The problem with drugs in traffic is often encountered when assessing the actual safe driving capability of a person in a given moment, for example after a car accident or a police check, or medical check-ups that are required for a driving license. The Road Traffic Safety Law considers methadone a drug. Drug addicts do not meet the health standards required of drivers. This research program deals with the attitude of drivers who are in methadone maintenance treatment programs with respect to the driving ability as well as the effects of methadone use in combination with other drugs on driving. It has been established that drivers undergoing the methadone maintenance program, regularly drive not only under the influence of methadone but also under the influence of marijuana (20%) and heroin (18%) and sometimes under the influence of marijuana (58.6%), heroin (55.7%), and alcohol (48.6%). Certain initiatives have been taken by some therapists to give, under certain circumstances, a clean bill of health to responsible methadone maintenance patients who have an adequate level of responsibility for themselves and their deeds, in order to help them obtain a driving license. Since it has been established that methadone maintenance patients use methadone quite commonly in combination with illegal drugs and/or alcohol, the classification of this type of addicts among possible driving candidates remains disputable. Long term interdisciplinary research is still required to determine the basic principles required to asses and possibly admit this type of drivers to participate in traffic, as well as to determine which professional therapists can participate and evaluate the driving capabilities of these patients.