The aim in this survey was analysis of contribution of exposure to tobacco smoke and selected socioeconomic factors in occurrence of low birth weight. The research was done on the group of 1528 pregnant women. Smoking habit was declared by 18.2% of women and passive exposure to tobacco smoke was stated by 31% of respondents. Significant association between active and passive smoking and socioeconomic status of respondents was observed. Cigarette smoking during pregnancy was the main cause of lower birth weight of newborns. The newborns of actively smoking mothers were lighter of about 332 g according to those ones of mothers who did not smoke and were not exposed to passive smoking, and were lighter than newborns of mothers who were not exposed to passive smoking of about 342 g.