Shakur Stevenson and Michael Conlan's upcoming fights in New York "cannot proceed in light of the ongoing coronavirus crisis" so have been postponed.
The events headlined by both boxers were scheduled for Saturday and Tuesday respectively at the Hulu Theater at Madison Square Garden.
Promoters Top Rank have been forced to postpone both events "after close consultation with the New York State Athletic Commission".
A statement read: "The health and safety of the fighters and their teams, and everyone involved in the promotion of these events, necessitated taking this step."
Stevenson was due to defend his world featherweight title against Miguel Marriaga and Conlan was set to face Belmar Preciado on St. Patrick's Day.
Just 24 hours earlier Stevenson and Conlan's fights were expected to go ahead but behind closed doors.
James Kirkland vs Marcos Hernandez, scheduled for Saturday in Maryland, has also been postponed "in the interest of public health".
Promoters Premier Boxing Champions said: "We understand how disappointing this is to boxing fans and regret any inconvenience."
As the coronavirus pandemic continues, Sky Sports News will broadcast three special programmes on Friday at 5pm, 6pm and 10pm (UK time) - Coronavirus In Sport.