Patients aged 18 to 73 years and diagnosed with non-organic insomnia according to ICD-10 (F 51.0) were treated in a multicentre, double-blind, randomised parallel group comparison with either 600 mg/die valerian extract LI 156 (Sedonium) or 10 mg/die oxazepam taken for 6 weeks. A total of 202 outpatients with a mean duration of insomnia of 3.5 months at baseline were included at 24 study centres (general practices) in Germany. - Sleep quality (SQ) after 6 weeks measured by the Sleep Questionnaire B (SF-B; CIPS 1996) showed that 600 mg/die valerian extract LI 156 was at least as efficacious as a treatment with 10 mg/die oxazepam. Both treatments markedly increased sleep quality compared with baseline (p <0.01). The other SF-B subscales, i.e. feeling of refreshment after sleep (GES), psychic stability in the evening (PSYA), psychic exhaustion in the evening (PSYE), psychosomatic symptoms in the sleep phase (PSS), dream recall (TRME), and duration of sleep confirmed similar effects of both treatments. Clinical Global Impressions scale (CGI) and Global Assessment of Efficacy by investigator and patient, again, showed similar effects of both treatments. Adverse events occurred in 29 patients (28.4%) receiving valerian extract LI 156 and 36 patients (36.0%) under oxazepam, and were all rated mild to moderate. No serious adverse drug reactions were reported in either group. Most patients assessed their respective treatment as very good (82.8% in the valerian group, 73.4% in the oxazepam group). During the 6 week treatment phase Valerian extract LI 156 (Sedonium) 600 mg/die showed a comparable efficacy to 10 mg/die oxazepam in the therapy of non-organic insomnia.