The new city fire commissioner is restoring staffing levels at 49 of the city's engine companies.
Fire Commissioner Salvatore Cassano says the fifth firefighter has been restored to teams that were reduced to four firefighters last month.
The cuts were made after a rising number of firefighters called in sick, straining the overtime budget.
The annual medical leave rate for firefighters rose above 7.5 percent by December 1. That is the threshold at which the New York Fire Department begins to cut staff, and it is the third time in seven years the department has done so.
FDNY officials say absenteeism has dipped 16 percent since the cuts, which has allowed the department to add the staff again.