Objective: Tissue contains fluorophores that autofluoresce without additional dye or photosensitizer with the appropriate light excitation. This technique has been widely applied for discrimination between normal and precancerous tissue. The aim of this study was to explore the capability and reliability of autofluorescence phase determination in samples of human endometrium. Methods: A total of 70 measurement sites from 31 endometrial tissue samples from hysterectomy were enrolled. Xenon light (330 nm) was directed at the endometrial tissue and the resultant autofluorescence intensity recorded. Spectra were then grouped according to the proliferative and secretory phase, with multivariant analysis, partial least square (PLS) and analysis of variance (ANOVA) used for evaluation of the statistical significance of phase determination. Results: Both proliferative and secretory autofluorescence spectra showed a similar characteristic triple-peak curve shape pattern, however, each of the intensities at the three peaks between the two phases varied markedly (p < 0.01). PLS analysis confirmed that collagen, NADH and FAD autofluorescence were the principle determinants of endometrial spectrum; the sensitivity and specificity of phase determination by autofluorescent was 100% and 97%, respectively. Conclusion: Autofluorescence measurement provides real-time information on endometrial phase status and, based on our results, it appears reasonable to suggest that it may be promising as a clinical tool for prompt phase interpretation.