The detection of cervical intraepithelial neoplasia (CIN) in human uterine cervix is possible through the use of fluorescence and reflectance spectroscopy. Fluorescence and reflectance spectra were recorded from the cervix of over 200 patients. Classification performance for distinguishing high-grade CIN (CIN II and III) from normal squamous, normal columnar and metaplastic tissues is 84%. On average, the intensity of fluorescence for CIN II/III lesions is two-fold less than non-CIN II/III tissue. However, variability in the spectra, associated with specific patient, tissue and instrumental parameters, is also noted and tends to blur the distinction between tissue groups. In particular, the intensity of fluorescence was found to increase with patient's age. The magnitude of age-dependence was evaluated using spectra from two of the largest tissue groups: metaplasia (1089 sites in 90 patients) and normal squamous mucosa (763 sites in 56 patients). The metaplasia class shows a stronger age dependence compared to normal squamous tissue: 7.5%/yr versus 2.6%/yr at 390 nm and 2.8%/yr versus 0.9%/yr at 460 nm, representing a two-fold increase in the intensity of fluorescence over 30 years. Hence, the accuracy of tissue classification algorithms may be improved with proper corrections to the spectra for these variables prior to classification.