Aim: This research is planned for analyzing the effects on smoking during pregnancy on neonate health and placenta weight. Method: The population of this descriptive comparative and cross-sectional research is women who consulted the maternity ward of a private hospital in İstanbul between January 1st -March 1st 2015. The sampling of the research is 115 volunteer puerperant (50 smokers and 65 non smokers) who consulted the maternity ward of the hospital between these dates, who are eligible for the inclusion criteria of the research. The data are collected through a questionnaire which is prepared by the researchers in order to evaluate the socio-demographical, obstetrical specifications of these women and the neonatal results. After the labor the placenta weight is measured. The necessary permission and ethical committee approval is received from the institution where the research is realized. Results: The case and control groups are similar in socio-demographic specifications such as age (p=0.259), educational status (p=0.725), working status (p=0.862), income level (p=1.000), marriage age (p=0.498) and obstetrical-gynecological specifications such as approximate pregnancy number (p=0.188), birth number (p=0.779), miscarriage number (p=0.587), abortion number (p=0.273), alive children number (p=0.779). It is determined that the women who smoked during pregnancy, smoke approximately 9,00±4,80 (min;2-max;20) cigarettes and 76% of them have at least one person who smokes in their family. When smoker and non smoker groups are compared a difference is determined for the average weight of babies at birth (p=0.002), average height (p=0.040), average placenta weight (p=0.000), but no statistically significant difference is determined for approximate head circumference (p=0.385), 1.min. APGAR score (p=0.963), 5.min. APGAR score (p=0.159) and congenital anomaly. Conclusion: It is determined that the babies of the women who smoke during their pregnancy have lower average birth weight and average placenta weight than the babies of the women who don't smoke during their pregnancy.