Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.
Form 20-F [ X ]      Form 40-F [   ]

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):  

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):  

On March 19, 2018, Motif Bio plc (the “Company”) issued a regulatory news service announcement, a copy of which is attached as Exhibit 99.1 to this report on Form 6-K, announcing the Company's participation at upcoming conferences in March.

This report on Form 6-K (including the exhibits hereto) shall not be deemed to be “filed” for purposes of the Securities Exchange Act of 1934, as amended, and shall not be incorporated by reference into any filing under the Securities Act of 1933, as amended, except as shall be expressly set forth by specific reference in such filing.

Exhibits

Exhibit 99.1            Regulatory news service announcement issued by Motif Bio plc, dated March 19, 2018, entitled "Motif Bio to present at upcoming investor and scientific conferences"

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.