AbstractMultiple studies have considered the nanosilica-cationic starch system to be a retention/drainage aid; however its potential to improve strength has previously been neglected. This research focused on the effect of both nanosilica and cationic starch on certain crucial physical and mechanical properties of fine paper compared with a paper sheet containing no additives to evaluate how this system can compensate for using more filler in fine paper. In previous studies, it was suggested that the cationic starch-nanosilica system induces much tinier flocs and thus possibly results in better strength properties. In this respect, results revealed that cationic starch did, however, improve tensile index; this effect weakened at higher filler levels. Cationic starch and nanoparticles both improved internal bonding, while cationic starches’ effect was more prominent. With more filler, tear index suffered. Although addition of cationic starch partly compensated this negative effect with filled papers, nanoparticles did not seem to have an obvious effect. Therefore, cationic starch provided the limited potential of using more filler and nanoparticles may do it indirectly.