Abstract: The effects of antihypoxia and antiarrhythmia of five proto-compounds were studied. The results showed that an intraperitoneal dose of 25.6mg/kg of 13-methyl palmatine iodide(MPI), berberine chloride (BC) and 13-methyl berberine iodide (MBI) had significant protective effect on hypoxia in mice,but palmatine chloride (PC) and jatrorrhizine chloride (JC) had no such effect. It was also evident that the chloroform-induced arrhythmia in mice could be antagonised by BC. MBI and JC intraperitoneally, but compounds PC and MPI were ineffective. The ED50 of BC. MBI and JC antagonising the chloroforminduced arrhythmia in mice were 14.9±0.10. 16.5±O.06 and 15.8±0.12 mg/kg (x±S.E. ) respectively. BC was effective to antagonise the aconidine-induced ventricular fibrillation but had not any effect on arrhythmias induced by ouabain. The structure—activity relationship of five compounds were discussed. The groups at 13(R4). 2(R) and 3(R1) position of moiety seemed to be related to the antihypoxic and antiarrhythmic effects.