Blue horizontal branch stars in metal-rich globular clusters I. NGC 6388 and NGC 6441

We report the first results of an ongoing spectroscopic survey of blue hori zontal branch stars in the metal-rich ([Fe/H] similar or equal to -0.5) glo bular clusters NGC 6388 and NGC 6441. Based on data obtained with the ESO-N ew Technology Telescope (NTT), we provide gravities and temperatures for fo ur stars in NGC 6388 and three stars in NGC 6441. These results are margina lly inconsistent with the predictions of canonical evolutionary theory, but disagree strongly with all non-canonical scenarios that explain the sloped horizontal branches seen in the colour-magnitude diagrams of these cluster s.