Evaluation of human papillomavirus (HPV) diversity in various grades of cervical lesions is helpful for understanding the characteristics of HPV infection in the pathogenesis of cervical neoplasia. A total of 227 women with normal cervices (n = 72), low- and high-grade cervical squamous intraepithelial lesions (SILs) (n = 55 and 53, respectively) and cervical carcinomas (n = 47) were screened for human papillomavirus (HPV) types 6, 11, 16 and 18 infection by the polymerase chain reaction. The prevalence of multiple HPV infections in patients with normal cervices, low-grade SILs, high-grade SILs and cervical carcinomas was 22.2%, 61.8%, 41.5% and 21.3%, respectively, while the prevalence of a single-type infection was 36.1%, 21.8%, 30.2% and 61.7%, respectively. HPV 16/11 and 16/18 were the most common combinations observed in multiple infections. Multiple HPV infections were seen most frequently in patients with low-grade SILs, and the prevalence decreased with increasing severity of cervical neoplasia. In contrast, infection with a single HPV type was most commonly observed in patients with cervical carcinoma, and the prevalence decreased with decreasing severity of cervical neoplasia. HPV 16 was the predominant single-type infection in patients with cervical carcinoma and this prevalence decreased steadily with decreasing severity of cervical neoplasia. Conversely HPV 11 was the predominant single-type infection in patients with normal cervices. This prevalence decreased with increasing severity of cervical neoplasia. Patients with low-grade SILs had a higher prevalence of HPVs, regardless of single or multiple infection status, and larger copy numbers of virus genome were seen more frequently in patients with more severe lesions.