Silver nanoparticles (AgNPs) are known to have antimicrobial effects, why it is being used in agriculture, water treatment and health sector. In this context, this study aimed to evaluate the in vitro antifungal activity of AgNPs against the phytopathogenic fungi Rhizoctonia solani isolated from infected tomato plants. The antifungal effect of AgNPs was compared to two conventional pesticides namely, thyophenate-methyl (Topsin-M) and ethylene-bis-dithiocarbamate (Mancozeb).Furthermore, the synergistic effect of AgNPs was evaluated when mixed with Topsin-M and Mancozeb. Comparable results for inhibition of mycelial growth were reported for AgNPs and Topsin-M with percentages of 92.2% and 94.1%, respectively. AgNPs were more efficient in inhibiting mycelial growth of R. solani compared to Mancozeb. Synergistic effects were observed when AgNPs were combined with the conventional fungicides. This study highlighted the promising efficiency of AgNPs in controlling phytopathogenic fungus alone or in combination with other conventional pesticides.