The A3 report is a Kaizen tool that must contain, on one side of an A3 paper sheet, a context, the current situation, the objective, an analysis, countermeasures, an action plan, the monitoring and an upgrade regarding the situation to be improved. This study seeks to analyze the post-implementation effects of the A3 tool, which is part of the Kaizen method. The research method consisted in the collection and evaluation of A3 reports produced in the past seven years in a company of pre-fabricated steel structures. Among the 154 developed A3 reports, it was observed that 76% were drafted by the engineering and manufacturing departments, which converged on the improvement of processes, services and innovative solutions. The manufacturing and assembly sectors had 60% of the improvements implemented by the A3 tool, but the impacts with the greatest economic significance for the company were found in other sectors, such as sales and logistics. The conclusion is drawn that the A3 report was effective in the deployment of Kaizen, resulting in the improvement of services and processes, and consequently in the direct reduction of the cost of the finished product. In addition, it influenced market and business expansion strategies throughout the company.