Propofol is a short-acting intravenous anesthetic agent with potential neuroprotective effect. In this study, we aim to investigate whether delayed propofol treatment is protective against lipopolysaccharide (LPS)-stimulated inflammatory responses in microglial cells. Cultured BV2 microglial cells were exposed to propofol at various time points after initiation of LPS stimulation. Nitrite production and cell viability were assessed after stimulation with LPS for 24 h. The effect of propofol on mRNA levels of cyclooxygenase-2 (Cox-2), interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS), tumor necrosis factor α (TNF-α) and interleukin-1β (IL-1β) was analyzed using reverse transcription PCR (RT-PCR) 6 h after LPS stimulation. The production of TNF-α and reactive oxygen species was also studied. Propofol applied 0–4 h after the initiation of LPS dose-dependently inhibits nitric oxide production. Propofol application also decreased LPS-induced Cox-2, IL-6, iNOS, TNF-α, and IL-1β mRNA expression and induced significant protein kinase B (PKB) phosphorylation in BV2 cells. Treatment with phosphoinositide 3-kinase (PI3K)/PKB inhibitor wortmannin decreased PKB phosphorylation induced by propofol, and abolished the inhibitory effect of propofol on LPS-stimulated NO, reactive oxygen species and TNF-α production. Our results suggest that delayed propofol treatment can reduce LPS-induced activation of microglial cells. These effects may be mediated by activation of the PI3K/PKB pathway.