Aim: Purpose of study is to validate COMPASS 3D patient specific quality-assurance software with Monaco treatment planning system (TPS) for routine quality assurance. Materials & methods: Purpose is to test the MLC modelling in COMPASS software, using Elekta Express QA package contains eight QA fields as follows (i) 10x10 (ii) 20x20 (iii) 3ABUT (iv) DMLC1 (v) HIMRT (vi) HDMLC(vii) 7SegA (viii) Four L were measured with COMPASS and compared with Monaco TPS. For clinical validation of COMPASS, VMAT plans were created for downloadable contoured structure set of AAPM TG119 cases for energy 6MV using Monaco (5.11) TPS for Versa-HD linear-accelerator and verified by COMPASS (calculated and measured). Results: For express QA check, all beams showed gamma pass-rate above 95% except for FourL field. FourL field Monaco versus COMPASS reconstructed gamma pass-rate was 98.4% but Monaco versus COMPASS computed gamma pass rate was 93.4%. COMPASS computed and measured, TG119 test cases showed good agreement with Monaco TPS, except some higher variation in low dose region. Conclusion: COMPASS measured (reconstructed) and computed results are in good agreement with Monaco TPS, therefore can be used for routine patient-specific quality-assurance. Special consideration has to be taken for superficially located targets.