In　this　paper,　we　consider　the　vanishing　viscosity　limit　problem　for　a　system　arising　from　the　Keller-Segel　equations　in　three　space　dimensions.　First,　we　construct　an　accurate　approximate　solution　that　incorporates　the　effects　of　boundary　layers.　Then,　we　prove　the　structural　stability　of　the　approximate　solution　as　the　chemical　diffusion　coefficient　tends　to　zero.　Our　approach　is　based　on　the　method　of　matched　asymptotic　expansions　of　singular　perturbation　theory　and　the　classical　energy　estimates.