Rotational transfer cross sections for the OH A2∑+ (v = 0) rovibronic levels were determined for collisions with water vapor at flame temperatures. OH fluorescence was induced by a 10-ns pulse from a Nd:YAG pumped dye laser, and the resulting fluorescence spectrum was recorded at selected times during the laser pulse. The measurements were performed in the postflame region of 30-Torr stoichiometric hydrogen/oxygen/nitrogen flames. Four different upper rotational levels were excited. State-to-state and total rotational transfer rates were calculated by optimizing the agreement between experimental spectra and synthetic spectra generated by a time-dependent numerical code. For the F1(1), F1(4), F2(5), and F1(10) upper rotational levels in the A2∑+ (v = 0) manifold, total rotational transfer cross sections were found to be (110 ± 30), (170 ± 60), (190 ± 60), and (110 ± 30) × 10−16 cm2, respectively, for collisions of OH with water vapor.