Single‐chain variable antibody fragments (scFvs) are molecules with immense therapeutic and diagnostic potential. Knowledge of their three‐dimensional structure is important for understanding their antigen‐binding mode as well as for protein‐engineering approaches such as antibody humanization. A major obstacle to the crystallization of single‐chain variable antibody fragments is their relatively poor homogeneity caused by spontaneous oligomerization. A new approach to optimization of the crystallizability of single‐chain variable antibody fragments is demonstrated using a representative single‐chain variable fragment derived from the anti‐CD3 antibody MEM‐57. A Thermofluor‐based assay was utilized to screen for optimal conditions for antibody‐fragment stability and homogeneity. Such an optimization of the protein storage buffer led to a significantly improved ability of the scFv MEM‐57 to yield crystals.