The article presents the influence of cutting parameters (F, V) on machined surface roughness (Ra) determined when milling C45 steel with a face milling cutter mounted on a piece of hard alloy. By experimental research, a regression model of roughness was built as an exponential function of the cutting parameters (cutting speed, feed amount). This regression model has been tested using mathematical statistical tools with a reliability greater than 94.9%. In addition, the influence of cutting parameters on surface roughness during machining has also been determined. In particular, when increasing the feed rate (F) and cutting depth (t), the roughness (Ra) increases, and when increasing the cutting speed.The article presents the influence of cutting parameters (F, V) on machined surface roughness (Ra) determined when milling C45 steel with a face milling cutter mounted on a piece of hard alloy. By experimental research, a regression model of roughness was built as an exponential function of the cutting parameters (cutting speed, feed amount). This regression model has been tested using mathematical statistical tools with a reliability greater than 94.9%. In addition, the influence of cutting parameters on surface roughness during machining has also been determined. In particular, when increasing the feed rate (F) and cutting depth (t), the roughness (Ra) increases, and when increasing the cutting speed.