We report six cases of protein S deficiency secondary to varicella. Five cases were complicated by thrombotic and vascular events, namely purpura fulminans and necrotic vasculitis, deep vein thrombosis and stroke. Two cases were associated with protein C deficiency and one case revealed a heterozygous factor XII deficiency. The underlying mechanism of this acquired protein S deficiency is unclear but could be related to a direct effect of zoster virus.