Lavandula stoechas L. (Lamiaceae) has been used for a long time in traditional medicine as an anticonvulsant and antispasmodic. The aqueous-methanolic extract of L. stoechas flowers (LS) was studied for its possible anticonvulsant and antispasmodic activities. When tested in mice, LS (600 mg/kg) significantly reduced the severity and increased the latency of convulsions induced by pentylene tetrazole (PTZ). LS likewise reduced PTZ's lethality. LS up to a dose of 600 mg/kg was found devoid of any hypnotic effect in mice, however, animals were found to be dull, calm and relaxed. The sedative effect of the plant extract was confirmed, as it prolonged the pentobarbital sleeping time in mice similar to that of diazepam. In isolated rabbit jejunum preparations, LS caused a dose-dependent (0.1-1.0 mg/ml) relaxation of spontaneous contractions. LS also inhibited K(+)-induced contractions in a similar dose range, thereby suggesting calcium channel blockade. This effect was confirmed when pretreatment of the jejunum preparation with LS produced a dose-dependent shift of the Ca(2+) dose-response curve to the right, similar to the effect of verapamil, a standard calcium channel blocker. These data indicate that the plant extract exhibits anticonvulsant and antispasmodic activities. Its calcium channel blocking property may be mechanistically related to these activities. Its usefulness in folk medicine appears thus to be based on a sound mechanistic background.