Tracking individual swine flu cases is too overwhelming for countries where the virus is spreading widely, the agency says in a statement.
WHO will no longer issue global totals of swine flu cases, although it will continue to track the global epidemic.
WHO says countries should look for signs the virus is mutating, such as changes in the way swine flu is spreading, surges in hospital visits or more severe cases.
The agency asks countries to report their first confirmed cases, then provide weekly case numbers with a description of their outbreaks.
WHO had reported nearly 95,000 cases including 429 deaths worldwide.
But the numbers are outdated, with Britain estimating it had 55,000 new cases last week alone.