High frequency magnetic activity with characteristics expected of toroidicity-induced Alfven eigenmodes (TAEs) has been observed in JET discharges heated by neutral beam injection and ion cyclotron resonance heating. The mode frequency is found to scale in the expected way with the magnetic field and plasma density and the frequency spectra show the characteristic multi-mode TAE structures seen in other devices. A correlation between fast particle loss levels and the mode amplitude is also suggested by the data.