Subsetting a data frame to the rows not appearing in another data frame

I have a data frame A with observations

    Var1   Var2  Var3
     1       3    4
     2       5    6
     4       5    7
     4       5    8
     6       7    9

and data frame B with observations

    Var1   Var2  Var3
     1       3    4
     2       5    6

which is basically a subset of A. Now I want to select observations in A NOT in B, i.e, the data frame C with observations

    Var1   Var2  Var3
     4       5    7
     4       5    8
     6       7    9

Is there a way I can do this in R? The data frames I've used are just arbitrary data.