Ionization-probabilities of NO molecules electronically excited in the A (2) Sigma(+) and B (2) Pi states have been determined by (1+1) resonance-enhanced, two-photon ionization. Various vibrational levels within these states have been excited prior to ionization. Measurements of the unsaturated ionization signal yields accurate values for the relative detection probabilities of NO of 1:(0.70+/-0.07) : (0.67+/-0.11) for excitation via the gamma(0-0), gamma(1-1), and gamma(2-2) bands, respectively, and (3.7+/-0.36)x10(-7) and (5.8+/-0.65)x10(-4) for ionization through beta(0-0) and beta(2-1) bands, respectively. Applying published data for the gamma- and beta-band transition probabilities allows the deduction of the ionization cross section of A (2) Sigma(+) and B (2) Pi vibrational states. The respective deduction of the ionization cross section of A (2) Pi(+) and B (2) Pi vibrational states. The respective ionization cross sections are (7.0+/-0.9)x10(-19) cm(2), (8.5+/-0.8)x10(-19) cm(2), (6.0+/-1.0)x10(-19) cm(2) for A (2) Sigma(+)(upsilon’=0, 1, and 2) and (5.0+/-0.5)x10(-21) cm(2) and (1.7+/-0.2)x10(-20) cm(2) for B (2) Pi(upsilon’= 0 and 2). These values are based on the experimentally determined cross section for A (2) Sigma(+)(upsilon’=0). Using a larger theoretical cross section for this state the other cross sections scale accordingly, within the experimental uncertainties.