Abstract. There is only one pair of non-real zeros of ζ (s), and of ζ (s), in the left half-plane. The Riemann Hypothesis implies that ζ (s) and ζ (s) have no zeros in the strip 0 ≤ s < It was shown by Speiser [3] that the Riemann Hypothesis is equivalent to ζ (s) having no zeros in 0 < σ < 1 2 (as usual we write s = σ + it). Levinson and Montgomery [2] gave a different proof; moreover, they showed that ζ (k) (s) has at most a finite number of non-real zeros in σ <