A selective breeding programme of Nile tilapia (Oreochromis niloticus) based on a fully pedigreed population of the GIFT (Genetically Improved Farmed Tilapia) strain has been carried out using Best Linear Unbiased Prediction (BLUP) method for genetic evaluation and selection. Two lines were created from the 2002 progeny; one selected based on high breeding values (selection line) and another one was selected for average breeding values (control line) for live weight (LW). The estimate of heritability for live weight at harvest was 0.24 ± 0.031, indicating that there is still abundant genetic variation and scope for further genetic improvement. The accumulated response was 107% in the latest generation of 2011, averaging 11.9% per generation. It can be concluded that although the selection programme in the nucleus of the GIFT strain in Malaysia resulted in significant improvement in harvest weight, there still exists an abundant genetic variation thus providing the scope for further enhancement in performance of this population.