This paper presents the employment of Design of Experiments (DoE) as the prediction tool for the laser micro-machining process. Laser internal micro-channels machined using pulsed Nd:YVO4 laser in PMMA were studied. The experiments were carried out according to 33 factorial Design of Experiment (DoE). In this paper the input process control parameters were laser power, P; pulse repetition frequency, PRF; and sample translation speed, U. The channel width and the micro-machining operating cost per metre of produced micro-channels were the measured responses. The responses were adequately predicted within the considered micro-machining parameters limits. For both responses, quadratic polynomial regression equations were constructed. The developed regression equations can be utilised to find optimal micro-machining process parameters within the studied process limits under experimental and operational conditions.