AbstractEscherichia coli and other Enterobacteriaceae thrive in robust biofilm communities through the coproduction of curli amyloid fibers and phosphoethanolamine cellulose. Curli promote adhesion to abiotic surfaces and plant and human host tissues and are associated with pathogenesis in urinary tract infection and food‐borne illness. The production of curli in the host has also been implicated in the pathogenesis of neurodegenerative diseases. We report that the natural product nordihydroguaiaretic acid (NDGA) is effective as a curlicide in E. coli. NDGA prevents CsgA polymerization in vitro in a dose‐dependent manner. NDGA selectively inhibits cell‐associated curli assembly and inhibits uropathogenic E. coli biofilm formation. More broadly, this work emphasizes the ability to evaluate and identify bioactive amyloid assembly inhibitors by using the powerful gene‐directed amyloid biogenesis machinery in E. coli.