BACKGROUND Sheng-Mai-San (SMS) has been used for the treatment of cardiovascular disease for many years in China. OBJECTIVE This study investigated the protective effects and active ingredients of SMS on myocardial injury (MI) in mice. METHODS SMS and n-butanol extraction of SMS (SMS-Bu) were prepared and administered to ISO-treated mice once a day for 7 consecutive days. The doses were equivalent to the raw medicinal herbs of SMS 5.72, 2.86 and 1.43 g/kg/d, respectively. Propranolol was used as positive control. Serum biomarkers, histopathological and electrocardiographic were evaluated. RESULTS Serum lactate dehydrogenase, creatine kinase and myeloperoxidase increased to 4473.6 ± 322.5, 950.0 ± 35.0 and 90.4 ± 12.2 U/L in the model group. SMS and SMS-Bu groups showed a decrease from 10 to 29% for lactate dehydrogenase and from 17 to 42% for creatine kinase, respectively. Both SMS and SMS-Bu significantly attenuated the myeloperoxidase activities (from 42 to 56%) and malondialdehyde levels (from 25 to 45%) compared with the model group. Decreased superoxide dismutase activities in ISO-treated mice were elevated from 19 to 59% when treated with SMS and SMS-Bu. These biochemical results were supported by electrocardiogram (ECG) and histopathological observations. Furthermore, 8 ginsenosides and 16 lignans were identified in SMS-Bu. CONCLUSIONS These findings suggested that SMS-Bu was the mainly active fraction of SMS which exerted its beneficial effects on MI mainly through protecting myocardial tissue and reducing oxidative damage, and the ginsenosides and lignans may serve as active ingredients of SMS for the treatment of MI.