Relaxation times of tissues can depend on tissue orientation with respect to main magnetic field. However, these effects are still unknown in many biological tissues. Relaxation anisotropy provides a base to develop novel quantitative MRI contrasts and unwrap the theory behind different relaxation mechanisms. We investigated relaxation anisotropy of conventional and rotating frame relaxation parameters in brain, spinal cord, tendon, cartilage, kidney and cardiac muscle tissue. The findings show that relaxation anisotropy varies between relaxation parameters and between different tissue types.