With extensive production and various applications of silica nanoparticles (SiNPs), there isa controversy regarding the ecotoxicological impacts of SiNPs. Therefore, the currentstudy was aimed to assess the acute toxicity of silica nanoparticles in maleRattusnorvegicus domesticaafter 24 and 96 h. Hematological, serum biochemical, stressbiomarker, and immune-antioxidant parameters were addressed. Chemicalcomposition, crystal structure, and the particle shape and morphology of SiNPs wereinvestigated using XRD, FTIR, BET, UV-Vis, and SEM, while TEM was used to estimate theaverage size distribution of particles. For the exposure experiment, 48 male rats weredivided into four groups (12 rat/group) and gavaged daily with different levels of zero(control), 5, 10, and 20 mg of SiNPs corresponding to zero, 31.25, 62.5, and 125 mg perkg of body weight. Sampling was carried out after 24 and 96 h. Relative to the controlgroup, the exposure to SiNPs induced clear behavioral changes such as inactivity,lethargy, aggressiveness, and screaming. In a dose-dependent manner, the behaviorscores recorded the highest values. Pairwise comparisons with the control demonstrateda significant (p<0.05) decrease in hematological and immunological biomarkers[lysozymes and alternative complement activity (ACH50)] with a concomitant reductionn the antioxidant enzymes [catalase (CAT), glutathione peroxidase (GPx), and superoxidedismutase (SOD)] in all exposed groups to SiNPs. On the contrary, there was a noticeableincrease in biochemical parameters (glucose, cortisol, creatinine, urea, low-densitylipoproteins (LDL), high-density lipoproteins (HDL), total protein, and albumin) andhepato-renal indicators, including alkaline phosphatase (ALP), alanine aminotransferase(ALT), and aspartate aminotransferase (AST), of all SiNP-exposed groups. It was observedthat SiNPs induced acute toxicity, either after 24 h or 96 h, post-exposure of rats to SiNPsevidenced by ethological changes, hepato-renal dysfunction, hyperlipemia, and severesuppression in hematological, protein, stress, and immune-antioxidant biomarkersreflecting an impaired physiological status. The obtained outcomes create a foundationfor future research to consider the acute toxicity of nanoparticles to preserve human healthand sustain the environment.