The basic task of in-line inspection is the early detection of potentially hazardous pipeline anomalies as well as their precise sizing thus providing useful input data for integrity assessment. For the inspection of liquid pipelines ultrasonic tools offer specific advantages with regard to resolution as well as measurement accuracy. Over the last two decades inspection tools have been considerably improved by taking advantage of the progress in electronics, data processing technology and data storage capabilities as made available from other application areas. Further improvements are related to inspection speed, inspection range and online monitoring of medium properties in order to control medium-dependent inspection settings. Apart from hardware-driven developments, ultrasonic modeling is becoming more and more important as a supporting tool for a better understanding of ultrasonic signal behavior as well as for optimizing e.g. the sensor design. In the contribution recent developments and their benefit for ultrasonic in-line inspection will be presented and corroborated by inspection results.