[en] The use of luminescent lanthanide (III) ions as substitutional probes for Ca(II) in Ca-binding proteins is well established. Additional information concerning metal-ion environments and associated chiral structure of these systems can be obtained through the measurement of the circular polarization in the luminescence (CPL). In this work we report the first measurements at low concentrations of CPL from Eu(III) substituted for Ca(II) in Ca-binding proteins. Increased selectivity is obtained through wavelength-selective excitation of the ⁷F₀→⁵D₀ transition by a CW-dye laser. Circularly polarized luminescence is monitored in the ⁵D₀→⁷F₂ transition