Aims: It was the aim of this study to measure spectral transmission of the human crystalline lens in situ. Method: The crystalline lens was illuminated by one of four light-emitting diodes of different colors. The relative spectral transmittance of the human crystalline lens was measured with the Purkinje-Sanson mirror images over a wide range of ages. Result: The study evaluated 36 crystalline lenses of 28 subjects aged 21–76 years. There was a significant correlation between the age and spectral transmittance for blue light. Conclusion: Spectral transmittance of the crystalline lens in situ could be measured with Purkinje-Sanson mirror images.