Results from previous studies evaluating the effect of nail polish on oxygen saturation (SpO 2 ) determined by pulse oximeter monitors are inconsistent. Establishing the effect of nail polish on SpO 2 is relevant to clinical practice, since removing nail polish requires clinical time and supplies.The objective of this study was to determine if fingernail polish affects SpO 2 as measured by two different pulse oximeter machines.Absorption spectra of 10 nail polish colors were obtained by spectrophotometry. Twenty-seven healthy volunteers with SpO 2 ≥95% participated. Using the Nellcor N20 and N595 pulse oximeters, the mean SpO 2 was measured on each of 10 nails with and without nail polish and using a side-to-side configuration. Means were compared using paired t-tests.Mean SpO 2 had a statistically significant decrease with brown and blue nail polish using both machines (p<0.05) but this was not clinically significant (<1% difference). Using the side-to-side configuration, the N595 oximeter had a statistically significant decrease in mean SpO 2 with red nail polish but again this was not clinically significant.Fingernail polish does not cause a clinically significant change in pulse oximeter readings in healthy people.