Seedling and classification machines are still under specific development for most of the seeds commonly used in agriculture. Those machines well adapted to the plant physical requirements for breeding. Therefore, determination of physical properties of seeds is a very important subject to breeding for mechanization. Several physical, gravimetric, and frictional seed properties of six open pollinated melon (Cucumis melo L.) cultivars (Kirkagac 589, Altinbas 637, Vilmorin Depuis 1743, Muhurlu, Hasanbey, Ananas) were determined and compared in terms of 1000 unit mass, width, length, thickness, roundness, sphericity, bulk angle, specific bulk density, density, moisture content, mineral matter content, swelling capacity, and static fraction angle (aluminium, stainless steel, galvanized sheet metal, rubber, glass, MDF). The obtained data for the six melon cultivars, which might be useful to engineers in the equipment design, were generally found to be statistically different. These differences could be attributed to the individual characteristics of these cultivars.