BACKGROUND The aim of this study was to examine the occurrence and distribution of the general neuronal marker protein gene product (PGP) 9.5 in the cervix uteri. METHODS Cervical biopsies were obtained from late pregnant (n=5), postpartal (n=5) and non-pregnant (n=5) women. The samples were prepared for immunohistochemistry using antibodies to PGP 9.5. RESULTS Nerve fibers were found consistently in all biopsies. There were differences in the occurrence and distribution of PGP 9.5 immunoreactive nerve fibers and cells between the three groups. Immunoreactive nerve fibers were observed at a moderate to abundant frequency in the stroma and around arterial vessel walls, in all groups. Immunoreactive nerve fibers were also observed at high frequency within and around glandular epithelium in the late pregnant and postpartal groups. PGP 9.5 immunoreactive cells were seen occasionally in the stroma of the non-pregnant group, but at a high frequency in the stroma, around arterial blood vessel walls, around and within the glandular epithelium in the late pregnant and postpartal groups. The total frequency of immunoreactive nerve fibers and cells was the highest in the late pregnant group, slightly lower in the postpartal group, and the lowest in the non-pregnant group. CONCLUSIONS These findings show that changes in the general innervation take place during human cervical ripening until late pregnancy and parturition.