National Coordinator for Health Information Technology Farzad Mostashari announced his resignation Tuesday, two years after beginning his tenure at the helm of federal efforts to design and implement the government’s biggest health IT projects and four years after joining the U.S. Department of Health and Human Services.

The bow-tie wearing cheerleader for data’s power to transform healthcare did not reveal what he’d be doing next. But in an email to his staff, Mostashari said they could be assured that he would continue to be part of the “battle for healthcare transformation.” Meanwhile, he’ll continue in his current role while HHS searches for his replacement.

Mostashari joined the Office of the National Coordinator in 2009 as Principal Deputy National Coordinator and took over as the National Coordinator in 2011. Under his watch, the office defined the meaning of “meaningful use” of electronic health records, designed and set up many new federal grant programs intended to assist with health IT adoption, and rallied a growing community of health IT users and experts.

“During his tenure, ONC has been at the forefront of designing and implementing a number of initiatives to promote the adoption of health IT among health care providers,” wrote Health and Human Services Secretary Kathleen Sebelius in an email announcing the departure.

“There are formidable challenges still ahead for our community, and for ONC,” said Mostashari in his farewell email. “But none more difficult than what we have already accomplished.”

“We have been pioneers in a new landscape, but that landscape is one changed for ever, and for better,” he wrote.