Mounting evidence indicates that exosomes derived from human umbilical cord mesenchymal stem cells (hucMSCs-exosomes) combine the advantages of hucMSC pluripotency with their nanoscale dimensions, enhancing their clinical potential through prolonged circulation half-life. Despite these promising characteristics, research on their immunological toxicity remains insufficient. This study focuses on the impact of hucMSC-exosomes on the general toxicity and immunopathological indicators. When mice received tail vein injections of 6 × 10 hucMSC-exosomes particles, we observed no significant changes in body weight, feed intake, blood composition, organ indices, or histopathological findings throughout the 14 days observation period. Similarly, blood levels of immunoglobulins, cytokines, and lymphocyte subpopulations remained stable. The hucMSC-exosomes produced no detectable negative effects on immune organs including the thymus, spleen, and bone marrow. These findings indicate that intravenous administration of 6 × 10 particles of hucMSC-exosomes appears relatively safe at the murine level. This assessment of safety and immunological impact following intravenous hucMSC-exosomes infusion offers experimental support for potential clinical applications and future analyses in this field.