In the past two decades, researchers have been developing prepreg materials with matrix properties that can allow the elimination of the additional adhesive traditionally used between the core and the skins of composite sandwich structures. There have been several publications on self-adhesive prepreg used for sandwich structures; but none with a comparative study for primary structural application, from the same fabrication basis. This research focused on the properties of adhesiveless honeycomb sandwich structure with carbon graphite prepreg, while assessing the structure with adhesive film at the skin-to-core interface simultaneously. In the study, laminate and honeycomb sandwich panels were fabricated and tested with consistent lay-up, curing, and testing processes, all fully documented. Sandwich panels were made with the CYCOM 977-2 prepreg system from Cytec and the AF191 adhesive film from 3M, while the adhesiveless sandwich panel had the MTM45-1 prepreg systems from Advanced Composites Group (ACG). Laminate panels were also fabricated using the two different prepregs. Specimens from the panels where tested for physical and mechanical properties, as well as moisture absorption performance. The results obtained from the non-destructive testing and the experiments confirmed that the self-adhesive prepreg physical properties met the components and void content recommendations for use in primary structures. In addition to analysis of existing published data, mechanical tests were performed in room, hot and cold temperatures, as well as dry and wet conditions. The results suggested that aramid honeycomb sandwich structure with self-adhesive carbon graphite prepreg systems, alongside similar structure using additional adhesive, demonstrates the ability to be used for primary structure.