Petersen's theorem asserts that any cubic graph with at most 2 cut edg
es has a perfect matching. We generalize this classical result by show
ing that any cubic graph G = (V, E) with at most 1 cut edge has a T-jo
in of cardinality less than or equal to Absolute value of V/2 for ever
y even subset T of vertices. Our result is based on the Edmonds-Johnso
n min-max relation for T-joins.