Tool breakage has been successfully detected by Acoustic Emission in turning, milling and drilling. A new autoadaptive system has been developed and successfully tested in industrial conditions. Tool wear monitoring was also investigated in turning, milling, drilling and high speed milling. The cutting speed and the depth of cut are very important for the Acoustic Emission level. Acoustic Emission contains an information on the cutting processes and particularly on the tool wear but presently no general relationship between any Acoustic Emission parameter and tool wear can have been derived even if in some cases, Acoustic Emission changes is strongly related to tool modifications.