Several research have shown positive impact of gender preference on fertility in Iran, However new demographic conditions leave us facing two unanswered questions; in a modern low-fertility society, whether parents have preferred the gender of their children, and if so whether the gender preference is a strong predictor of the probability of having another child. To fill these gaps, this study uses data from two cross-sectional surveys in Tehran city in 2014 and 2017. The findings show that half of women intended to bear more children. 40 and 50% of women reported they prefer having children of one sex over another one in 2014 and 2017 respectively. While, preference for sons is rooted in Iranian culture and history, for Tehran, a new gender preference is emerging. Women whose have gender preference have a strong tendency towards a girl preference. We do not find significant effects of gender preference on fertility intention. In fact in the context of low fertility, Gender preference is not as a driving force in the continuing fertility. However the likelihood of intention to bear more children rose considerably if sex composition of their children was same. Most of families consider it important to have at least one daughter and one son.