Low progesterone levels are associated with luteal phase deficiency in women with polycystic ovary syndrome (PCOS). The mechanisms regulating progesterone biosynthesis in the granulosa cells from women with PCOS is largely unknown. Fractalkine is expressed in human ovaries, and is reported to regulate progesterone production in granulosa cells of healthy women. In the current study, we aimed to examine the role of fractalkine in women with PCOS. Reduced fractalkine levels were found in follicular fluid and granulosa cells, accompanied by decreased progesterone production and reduced steroidogenic acute regulatory protein (StAR) expression in the granulosa cells of patients with PCOS. Administration of fractalkine reversed the inhibition of progesterone and StAR expression. The mechanism mediating these effects may be associated with the inhibition of ERK activity in the granulosa cells from women with PCOS. Our findings revealed that fractalkine regulated steroidogenesis in follicular granulosa cells of women with PCOS.