This report consists of a review of 18 individuals stopped or arrested for erratic driving (sometimes including accidents) combined with a review of literature relevant to the effects of ecstasy or MDMA on driving. The literature reviewed included clinical studies of the effects of MDMA on driving or driving-related skills, retrospective reports of the effects of ecstasy / MDMA on driving, and case reports of impaired driving or traffic fatalities after ecstasy use. The authors note that not all case studies measured plasma or urinary MDMA. The authors also draw conclusions about 18 people stopped or arrested for various traffic offences in Washington state. Blood samples from all 18 cases were assessed for MDMA, MDA and other commonly used licit and illicit drugs (e.g. ethanol, THC and cannabanoids, benzodiazepines, amphetamines, and including LSD), with assessment done via GCMS, with various modifications used to increase detection of specific drugs. The presence of substances other than MDMA (including ethanol) was found in blood in 12/18 cases, but only MDMA was found in blood in 6/18. Range of plasma MDMA values was from < 0.05 (MDMA-alone) to 1.89 (MDMA + PCP). Blood MDMA concentrations in MDMA-alone cases ranged from < 0.05 to 0.58. Demeanor, coordination, balance and physiological signs assessed in all cases. The male/female ratio of drivers was 15/3, and male/female ratio for the 6 MDMA-only cases was 5/1. Average age was 21, the median 20, and for MDMA-only, age range was 18-25. 5/18 were involved in collisions, and 8/18 were involved in erratic driving. No formal analyses were performed, but cases were compared by comparing occurrences of each event, behavior, or sign. MDMA-only cases were distinguished from multiple drug users by lack of either vertical or horizontal nystagmus. (The authors state that elevated BT and BP are not observed, but data on multiple drug users is often missing, and BP in MDMA-alone cases appears comparable or higher to BP in MDMA + other drug cases. Intriguingly, cases of low-average BT appear in MDMA-alone as well as MDMA + other drug cases.) MDMA-alone cases appeared relaxed (mellow, overly laid back), yet also fidgety or with tremors present. Reckless driving did not seem to be related to blood MDMA level, either in multiple-drug or MDMA-alone cases. The review and synthesis suggests MDMA, alone or in combination with other drugs, is associated with impaired driving, due to one or more MDMA-induced effects. Relevant effects could be impaired concentration, impaired judgment, altered sense of time, or impaired/altered balance. The authors also hypothesize that persistent cognitive impairment associated with regular ecstasy use might exacerbate impaired driving acutely after MDMA, but do not offer supportive evidence. They identify some setting-related conditions, such as fatigue after prolonged dancing, which might also impair driving. This is the first report of impaired driving after MDMA use, with presence of drug confirmed in blood samples, and with impairment arising in naturalistic settings. The findings are in agreement of laboratory studies (Cami et al. 2000; Downing 1986) indicating that MDMA acutely impairs some cognitive and psychomotor processes used in driving.