In abrasive waterjet (AWJ) cutting system, the orifice and focusing tube undergo continuous wear due to which the quality and effectiveness of the process are affected. The present paper reports the experimental studies carried out to investigate the influence of orifice and focusing tube bore variation on the performance of abrasive waterjets in cutting 6063-T6 aluminum alloy. The performance was assessed in terms of different parameters such as depth of cut, kerf width and surface roughness. This study made use of Taguchi's design of experiments and analysis of variance (ANOVA) to analyze the performance of AWJs in cutting. These experimental data was used to build empirical models. An hybrid strategy combining the response equations of the empirical model with fuzzy model is proposed to arrive at suitable set of process parameters for achieving desired cutting performance considering the variation in orifice and focusing tube bore. The adequacy of the model is confirmed with suitable experiments. © 2006 Elsevier B.V. All rights reserved.