  Nancay radiotelescope is involved in high precision timing since 20 years.
Since 2004, a coherent dedispersion instrumentation enables numerous routine
observations on more than 200 pulsars using half of the time if this 100-meters
class radiotelescope. Two main programs are currently conducted. A large set of
young and old pulsars is timed for a multi-wavelength approach, complementary
to the very successful high energy observations of pulsars done by FERMI. A set
of highly stable millisecond pulsars is monitored as our contribution to the
European Pulsar Timing Array in order to probe the cosmological Gravitational
Wave Background.
