The flare of 16 December 1988 is one of the most intense gamma‐ray line events that the Gamma‐Ray Spectrometer (GRS) on SMM has recorded. It proceeded in several well separated bursts. By taking the fluences of selected energy bands, the spectrum of the primary particles can be determined. We find that it changes from burst to burst, suggesting even different acceleration mechanisms. ©1996 American Institute of Physics.