This paper presents a new approach developed for online measurement of fatigue crack growth (FCG) in an aluminium alloy. This paper also demonstrates the use of virtual instrumentation (VI) software that enables such measurement for compact tension (CT), middle tension (MT) and three point bend (TPB) specimens. The FCG is being monitored with the help of compliance-based measurement. For measuring the compliance, crack opening displacement (COD) gauge has been used. The software also performs data acquisition (DAQ) at intervals as crack length changes. The software was developed in LabVIEW 7.1 with implementation using NI's 6014 card. The validation of the software is being done by comparison with actual visual measurements. The author's intention is to use this approach and the software developed for experimental studies in laboratories and for use in typical FCG testing of aerospace, automotive and other components. © Copyright 2008, Inderscience Publishers.