To determine whether maternal smoking influences the relationship between bacterial vaginosis and fetal fibronectin, the presence of cervical or vaginal fetal fibronectin, the presence of bacterial vaginosis, and smoking status were determined for 2899 women at 24 weeks' gestation. Fetal fibronectin was more common among women with bacterial vaginosis, but maternal smoking did not increase the likelihood that women with bacterial vaginosis would have fetal fibronectin detected. A previously reported impact of maternal smoking status on the relationship between bacterial vaginosis and fetal fibronectin thus was not confirmed.