The effect of Huoxuequyu recipe on erythrocyte membrane Ca(2+)-ATPase activity in pregnant rats with passive smoking induced asymmetrical intrauterine growth retardation (IUGR) was observed. The rats were divided into three groups: control group, model group and treated group. The fetal mean birth weight and erythrocyte membrane Ca(2+)-ATPase activity were found to be decreased in the model group as compared with the control and treated groups. There was a significant difference between the model group and the control group (P < 0.01), while no significant difference existed between the treated group and the control group (P > 0.05). Furthermore, the findings indicated that the erythrocyte membrane Ca(2+)-ATPase activity seem to be positively correlated with the birth weight (P < 0.05). On the basis of our observation, it is believed that the Huoxuequyu decoction could increase erythrocyte membrane Ca(2+)-ATPase activity and promote blood circulation, thereby exerting a beneficial effect on fetal development.