The Neosho County, Kansas Health Department director says close to 200 students were absent from Chanute High School on Tuesday.
There were fewer absentees on Wednesday, but still a lot in a school with a total enrollment of about 600.
Many of the sick students report flu-like symptoms.
The health department is not testing for the H1N1 virus but assumes that is the virus in many of the flu cases.
Wednesday is the first day for states to order the H1N1 flu vaccine.
Kansas has reported the deaths of six people who had been diagnosed with the virus.
The flu has been confirmed in 55 of the state's 105 counties since the first cases occurred in late April.