In presented paper results of comparative studies into the roughness (very significant tribological factor) of surfaces after cutting using the AWJM method were presented. Cutting was performed on samples made of three materials: quenched and tampered alloy steel (1.2080), plastic (polyamide PA6) and mineral material (syenite). Variable parameters in the cutting process included: jet pressure and feed. As a result of measurements involving selected roughness parameters (Ra, Rz and Rq)It was discovered that the majority of variable factors had a significant effect on the cut surface roughness. It was also demonstrated that the contact method measurements cannot be performed with regard to plastics because the results are characterised by a very great scatter of results values, making them unreliable.