Ultrasonic velocity measurements have been made on polycrystalline bismuth as a function of temperature and pressure over the temperature and pressure ranges 23–160°C (at atmospheric pressure) and 0–28.4 kbar (at 23°C), respectively. Special care was taken with the room‐temperature and pressure measurements in an attempt to resolve discrepancies in previously reported sound velocity measurements. The data have been used to determine the pressure‐temperature dependences of various elastic parameters, including the (discontinuous) changes across the I–II and II–III phase boundaries. The pressure data are the first that have been taken under truly hydrostatic conditions, and they are compared to results obtained with solid pressure transmitting media.