This chapter describes the most commonly used methods for total protein determination in different laboratories’ routines, including nitrogen content determination and spectrophotometric methods. The methods are subdivided into protein-dye interaction, copper-protein interactions, and wavelength absorption (280 nm) by aromatic residues. The methods described here include the apparatus, material, and reagents related, protocol, notes, and troubleshooting. The protein composition and the sample matrix might influence protein determination, and when selecting the method that best suits your needs, consider the method’s different principles. Our goal is to provide the reader with relevant notes beside the main procedure, aiding in the better performance of each method.