  Using well-known methods we generalize (hyper)virial theorems to case of
singular potential. Discussion is carried on for most general second order
differential equation, which involves all physically interesting cases, such as
Schr\"odinger and two-body Klein-Gordon equations with singular potentials.
Some physical consequences are discussed. The connection with Feynman-Hellmann
like theorems are also considered and some relevant differences are underlined.
