Resonant-mass detectors of gravitational waves in the short- and medium-term future

We report on the status and on the perspectives of the resonant-mass detectors of gravitational waves. Bar detectors have reached burst sensitivity h =~4 * 10^-19, or, in spectral units, 3 * 10^-22 Hz^1/2 over bandwidth of about 1 Hz, with a duty cycle mainly limited by cryogenic operations. The strongest potential sources of gravitational wave bursts in our galaxy are today monitored by such instruments. In addition to the systematic search for impulsive events, the data collected are being used to detect periodic waves over long time periods, for giving new upper limits for the stochastic background of cosmological origin, and for studying possible correlation with gamma ray bursts. We report here the state of the art of such detectors and their short- and medium-term future.