Whilst internationally benzodiazepines are first choice for treatment of alcohol withdrawal syndrome, Germany has a long tradition with clomethiazole. This study explores effectiveness of clomethiazole versus oxazepam in the treatment of alcohol withdrawal syndrome within an observational, stratified, non-inferiority study in routine care. Main outcome criterion was severity of the alcohol withdrawal syndrome (Alcohol Withdrawal Syndrome [AWS]) Scale in the first five days. Additionally, the association between the detoxification protocol (five vs. ten days) and AWS-Score was examined. 453 patients (74.2 % male, average age 47.1 years [± 9.2]) took part; 249 received oxazepam (55.0 %) and 204 clomethiazole (45.0 %). The average duration of inpatient treatment was 14.0 days (± 6.3) in both groups. The average AWS-score was lower in the oxazepam group compared to the clomethiazole group (50.0 [± 26.5] vs. 56.2 [± 31.5]; p < .05; effect size d = - .25). Patients with a shorter detoxification protocol had a lower AWS sum score compared to patients with a longer protocol (p < .001; d = - .46). In treatment of alcohol withdrawal syndrome in routine care oxazepam yields at least comparable results to clomethiazole.