Nanostructures in dairy products were studied using laboratory small-angle X-ray scattering (SAXS). Using a high penetration Mo-Kα line, both milk and cheese were measured using the same shape and optics. The samples were low- and regular-fat milk, mozzarella cheese and hard cheese with different ripening periods. All samples were used in their “as obtained state” from the supermarket and no pre-treatment was used before SAXS measurements. Most of the SAXS profiles of milk and cheese showed two features. Sharp peaks corresponding to the chain structure of fat appeared in the region of q>1nm-1. The positions of peaks indicate the existence of a 2L structure in all samples except low-fat milk. In addition, a 3L structure appeared in the cheese with ripening of 22 months. The second feature was a shoulder observed in log-log plot. The position of the shoulder in milk and mozzarella cheese was about q=0.7nm-1, which has been attributed to colloidal calcium phosphate (CCP) in many papers. Similar shoulders have been observed in hard cheese with ripening of 2 and 6 months, while the position is about 0.3nm-1, which is lower than that of milk and mozzarella cheese. This suggests that growth of CCP size may occur during the cheese making process.