Scientific analysis proves that the marble used in four ancient sculptures related to the Attalid dedication in Pergamon (i.e., the Dying or Capitoline Gaul, the Suicidal or Ludovisi Gaul, the head of a Persian, and the head of a Greek) is white Docimian marble. A fifth sculpture related to the Lesser Dedication in Athens (i.e., the mounted Amazon killing a barbarian now in the Palazzo Massimo in Rome) is carved from Carrara marble. To identify the marble of the Large Gauls with confidence it was necessary to find a means to discriminate clearly between Docimian marble and the white marbles of the newly discovered quarry at Göktepe near Aphrodisias. The usual multi-method approach for marble identification, which combines petrographic, isotopic, and electron paramagnetic resonance data, proved to be unsuitable in this case. Additional techniques were tested, and the answer proved to be strontium trace analysis. The traditional description of the marble of the Large Gauls as “Asiatic” is commented on in the light of the new results, and the consequences of the possible chronology and place of manufacture of the sculptures are briefly discussed.