Summary. Using objective-prism plates taken with the 44-arcmin objective prism mounted on the UK Schmidt telescope, we have found 53 emission-line quasar candidates and 29 ultraviolet-excess objects (possible low-redshift quasars) in a 5x5 degree2 field centred on 12h27m, +13°30' (1950) in the Virgo cluster of galaxies. Eighteen of these 82 candidates were observed using the double spectrograph on the Palomar 5-metre telescope; 13 of the observed objects proved to be quasars. The broad-absorption-line QSO Q1232+134 is the first example of the class to show broad low-ionization absorption lines- such as Mgnλ2798A-in addition to the usual high-excitation lines such as NλA 1240 A. Although we find no conclusive evidence for quasar-galaxy associations in this field, there do exist non-uniformities in the distribution of the quasar candidates, which may merit further investigation. These objects will provide a useful network of probes for absorbing material in the Virgo cluster. The lines-of-sight to two of the confirmed quasars pass very close to NGC galaxies; the respective projected QSO-galaxy separations are only 4 and 11kpc at the assumed distance of the Virgo cluster.