Methods for preparing degarelix acetate are provided that include the steps of providing a suitable resin; deprotecting the resin with a diethylenetriamine solution; reacting sequentially the deprotected resin with different Fmoc protected amino acids; deprotecting the amino acid in each sequence with a diethylenetriamine solution in a stepwise fashion to yield a degarelix crude compound; and purifying the degarelix crude compound to yield pharmaceutically acceptable degarelix acetate. Methods of preparing degarelix acetate-mannitol premix and the resulting degarelix acetate-mannitol premix are also provided.