The determination of particle size is important in many fields, such as life sciences (nanomedicine, drug delivery, tissue engineering, bioanalysis), chemical, environmental sciences and industries. Turbidimetry is a quick and nondestructive method to estimate particle size following an easy-to-follow procedure. Curves of turbidity vs silica particle concentration in distilled water of various sizes were obtained with high precision using the TURBIDI.TTM. These curves can be used to build a reference curve for the determination of particle size.