The recent discovery that parity is not conserved in certain weak interactions has opened the question of the degree to which it is conserved in the strong interactions (internucleonic and electromagnetic). Parity non-conservation in such interactions may be detected by: (i) The violation of a selection rule which is absolute if parity is conserved. (ii) The presence of circular polarization of γ-rays or longitudinal polarization of heavy particles in reactions involving unpolarized initial systems and where the apparatus itself defines no screw sense. (iii) The presence of odd powers of cos θ in the angular distribution of radiations coming from well-defined nuclear states. Two experiments have been performed in class (i). The radiative capture 4 He(d, γ) 6 Li through the 0 + state at 3·57 MeV has been sought and its absence corresponds to F 2 < 1 X 10 -7 ( F is the relative strength of the parity non-conserving interaction). The reaction 7 Be( n , α)α with thermal neutrons has been sought and the limit on the cross-section corresponds to F 2 < 1 X 10 -7 .