It said Bill Seeger, a non-executive director, had assumed the role of interim CFO with immediate effect.
The company, which reported a 27 percent rise in first-half headline operating profit, said its outlook for the year remained in line with its previous guidance.
Shares in Smiths were down 1.2 percent 1,599p at 1007 GMT, making them one of the top five losers on the UK blue chip <.FTSE> index.
(The story was refiled to fix the headline)
(Reporting by Rahul B in BengaluruEditing by Jason Neely)