Four-dimensional N = 1 supersymmetric gauge theories with two adjoints and
a quartic superpotential are believed, from AdS/CFT duality, to have SL(2,
Z) invariance. In this note we review an old, unpublished argument for this
property, based solely on field theory. The technique involves a complexif
ied flavor rotation which deforms an N = 2 supersymmetric gauge theory with
matter to an N = 1 theory, leaving all holomorphic invariants unchanged. W
e apply this to the N = 1 gauge theory with two massless adjoints and show
that it has the same auxiliary torus as that of N = 4 gauge theory, from wh
ich SL(2, Z) invariance follows. In the appendix, we check that our argumen
ts are consistent with earlier work on the SU(2) case. Our technique is gen
eral and applies to many other N = 1 theories.