Background: Exposure to Second hand smoking (SHS) during pregnancy may endanger maternal and fetal health with long term consequences. The aim of this study was assess the knowledge, attitude, and practices of pregnant women in relation to environmental tobacco smoke exposure. Methods: A cross-sectional study was conducted among a convenience sample of pregnant women who had a routine obstetrical appointment in the obstetrical gynecology department of the university Hospital Farhat Hached Sousse. Results: Overall, 125 pregnant women were approached. The prevalence of exposure to SHS in pregnant women was 81.6%. The woman education level (p=0.001), the education level of the partner (p=0.002), living area (p=0.001) and the mother working statue (p=0.034) had significant association with the participant prevalence of exposure to SHS. The father’s level of education (high school or university level) seems to be a determinant factor of both SHS (p=0.006; OR 5.1; IC: [1.53-17.53]) and avoidance practice (p=0.04; OR 8.62; IC: [2.03-36.6]). Conclusions: We suggest strengthening health education for pregnant women on the health risks of active and passive smoking. These interventions should be comprehensive, multi-faceted and multi-sectorial involving primary health care providers, public health practitioners, policy makers, and media.