Abstract: This report presents the results obtained in a study aimed at optimizing the protective properties, in regard to ballistic resistance, of flexible ballistic panels of bulletproof vests with reduced panel weight. Attention is focused on one of the most commonly used bulletproof vests in Bulgaria - those with a level of protection IIIA, according to NIJ (standards of the US National Institute of Justice). The test was conducted in compliance with the conditions and methodology regulated in one of the leading standardization documents in this area - NIJ 0101.04 - Ballistic Resistance of Personal Body Armor. The weapons and their ammunitions used in Bulgaria and the region have been taken into account, as a result of which the samples of flexible ballistic panels of bulletproof vests are additionally tested with two more types of weapons. Analysis and evaluation of the obtained results are presented.