During gestation the developing fetus is dependent upon nutrient transfer from the mother which is mediated by the placenta. Fetal and placental growth responds to maternal influences such as circulating blood glucose levels and therefore may be adversely affected by abnormal homeostasis. The mammalian biological clock is based up on the rhythmic expression of clock and clock-controlled genes. Thus transcript-translational associations result in the synthesis of key regulatory and downstream proteins involved in various physiological and metabolic processes. It is thought that the master clock, located in the suprachiasmatic nucleus, orchestrates peripheral tissues in their own circadian rhythms and generates organism wide synchronicity [1]. Two essential components of the circadian clock which have been postulated to regulate glucose homeostasis are CLOCK and BMAL1 genes [2]. These two are considered ‘core clock genes’ and their activation leads to the subsequent synthesis of CLOCK and BMAL1 proteins that interact and inhibit protein production to create a negative feedback loop [3]. Both proteins have been identified in a range of peripheral tissues including the placenta, and we have previously reported that intermittent fasting causes an increase in CLOCK expression in the rat placenta. In this study we set out to identify whether the key circadian regulators were present in the human choriocarcinoma cell line, BeWo, and to establish whether their expression in this cell line can be manipulated via mechanisms previously reported to have this function in other models. BeWo cells were cultured 30°C at 5% CO2 conditions in DMEM media, 10% FBS, 2% penicillin-streptomycin at a range of glucose concentrations, 10, 20, 30, 45mmol for 3 passages. Nuclei isolates (n=3) and cytoplasmic fractions (n=3) were collected for further analysis and samples were subjected to separation via gel electrophoresis and transferred to PVDF membrane though electro-blotting. Immunostaining allowed for quantification of CLOCK and BMAL1. Analysis indicates that CLOCK and BMAL1 are present in the nucleus and the cytoplasm of BeWo cells. Results also show CLOCK expression is significantly down regulated (P<0.05) as glucose concentration increases in both the nucleus and the cytoplasmic fraction. By contrast BMAL-1 expression remains constant. These data suggest that BeWo maintains some workings of the circadian clock that can be explored to further our understanding about the placentas robust circadian control mechanisms.