A prospective study of cervical dysplasia cases and control cases matched for age and parity was undertaken in search of factors related to cervical carcinogenesis. Cytologic examination of 66,736 women revealed negative findings in 28.5%, inflammation in 70.3%, dysplasia in 1.4% and carcinoma in 0.1% of the cases. Data on epidemiologic features, cytomorphologic characteristics and serologic findings of antibodies to herpes simplex virus (HSV) were collected for proven cancer patients, dysplasia cases and control subjects. Cancer patients revealed significantly elevated antibodies to HSV as compared to the controls. The analysis revealed a higher proportion of dysplasia cases with an age at consummation of marriage of less than or equal to 15 years as compared to controls, with a relative risk of 1.5 (P less than .05). Similarly, a higher proportion of women with dysplasia had HSV-II-specific antibodies as compared to control women. The relative risk was found to be 1.3, which was not statistically significant (P greater than .05). The Mantel-Haenszel summary relative risk between antibodies to HSV and the two groups (dysplasia cases and controls), adjusted for the age at consummation of marriage, worked out to be 1.38, which was also statistically not significant (P greater than .05). The overall progression rate of dysplasia to malignancy was found to be 11.7% at the end of 54 months (during a total follow-up period of 84 months). Progression to cancer was highest in severe dysplasia cases and less in mild dysplasia cases. The progression rates were also significantly higher in the group of women who revealed antibodies to HSV II. Similar differences in the progression rates were observed with regard to the age at consummation of marriage.