Presentations are becoming an increasingly more common means of communication in working environments, and slides are often the necessary supporting material on which the presentations rely. In this paper, we describe a slide indexing and retrieval system in which the slides are captured as images (through a framegrabber) at the moment they are displayed during a presentation and then transcribed with an OCR system. In this context, we show that such an approach presents several advantages over the use of commercial software (API based) to obtain the slide transcriptions. We report a set of retrieval experiments conducted on a database of 26 real presentations (570 slides) collected at a workshop. The experiments show that the overall retrieval performance is close to that obtained using either a manual transcription of the slides or the API software. Moreover, the experiments show that the OCR based approach outperforms significantly the API in extracting the text embedded in images and figures.