Perivascular macrophages (PVMs) are a group of resident myeloid cells in the central nervous system (CNS) expressing the CD206 mannose receptor. They play dual roles: clearing harmful substances in healthy states and contributing to increased blood-brain barrier (BBB) in inflammatory states. To investigate their role in Amyotrophic lateral sclerosis (ALS) pathogenesis, we depleted PVMs at the presymptomatic stage in our ALS animal model and examined the effects on disease progression and neuroinflammation.In SOD1(G93A) mutated rats, PVM depletion was achieved via clodronate-loaded liposome intra-cisternal injections, with a control group receiving PBS-loaded liposomes. Three experimental groups were studied: early single injection, late single injection, and multiple injections. Rats were monitored until humane endpoints, assessing weight changes and locomotor activity to track disease progression.Results showed upregulation of CD206+ cells in various CNS regions of SOD1 rats at the endpoint, confirming PVM involvement in ALS pathogenesis. Following PVM depletion, a decrease in CD206+ cells was observed, indicating successful depletion. Weight change analysis indicated a delayed presymptomatic stage in the depleted group across all experiments. Behavioral studies demonstrated milder or delayed symptomatic stages, particularly with multiple injections. Immunofluorescence staining revealed upregulation of PVMs, astrocytes, and microglia in the depleted group's spinal cord ventral horn compared to controls at the endpoint.Depleting PVMs at the presymptomatic stage of ALS delays disease onset, particularly with repetitive doses of clodronate-loaded liposomes, suggesting a potential therapeutic avenue for ALS treatment.