The Pierre Auger Observatory is the largest and most important hybrid detector designed to investigate the origin and the nature of ultra-high energy cosmic rays (UHECR). The Observatoy has been in operation continuously since 2004, and during the currently more than 18 years of research has collected a huge amount of high-quality data which gave us knowledge about the origin of the most energetic particles ever observed in the Universe. This contribution will present the main results obtained in searches for neutral particles during Auger Phase1, i.e., the period before the installation of the upgrade AugerPrime. These include the searches for UHE photons, neutrinos and neutrons, which mainly made it possible to set upper limits on their fluxes and to search for excesses in the direction of candidate acceleration sources and transient events.