Measuring spectral BRDFs of physical surfaces is essential to applications in computer graphics, computer vision and image analysis. Such measurements provide spectral data to characterize surfaces that can be used for evaluating reflection models. Existing research on spectral BRDF measurements is very limited. This paper discusses two practical methods for measuring spectral BRDFs: the sample-fixed and sample-rotation methods. We will also present an effective interpolation method to convert the raw data into a regular format for convenient applications.