We define a function f : X → Y to be slightly β-continuous if for every clopen set V of Y , f−1(V)⊂ Cl(Int(Cl(f−1(V)))). We obtain several properties of such a function. Especially, we define the notion of ultra-regularizations of a topology and obtain interesting characterizations of slightly β-continuous functions by using it. 2000 Mathematics Subject Classification. 54C08.