Both the imaginary part (NIM) and the real part (NRE) of the complex index of refraction for Saharan aerosols have been determined as a function of wavelength between 300 and 700 nm: nRE was determined by means of an immersion oil technique, and nlM was determined from measurements of the total diffuse reflectance of the aerosol by means of an analysis using the Kubelka-Munk theory. No significant differences in the optical properties of the aerosol were seen among the samples collected at sampling sites on both sides of the Atlantic. Comparison of our results with others based on measurements of the ratio of the direct to the diffuse radiation shows that the two independent methods give remarkably similar results.