The goal of the paper is to study the impact of advertising on retail company key performance indicators (KPIs) and customer behavior in MAREA simulation model. The subject of the presented research are simulation experiments in MAREA software framework. The simulation model incorporates trading company dealing with retailing of computer cables. We base the simulations on two scenarios. In the first scenario, company does not use advertising at all during the observed period. In the second scenario, company uses advertising regularly during the simulation. In each scenario, simulation is 365 days long. The first scenario will serve as a basic one. We will use it to compare the effect of advertising on company KPIs and customers' behavior in the second scenario. Based on the simulation setup we determine and evaluate several hypotheses. In the paper, we firstly present a brief related works section from multi-agent simulation and marketing research domains. Secondly, we describe MAREA simulation framework and simulation setup. Finally, we present and discuss the impact of advertising and some implications.