The goal of this study was to investigate the expression levels of interleukin 6 (IL-6), nuclear factor kappa beta (NF-kappabeta), bone-specific alkaline phosphatase (BALP), and bone osteocalcin (BGP) in rats with osteoporosis and their significance in the pathogenesis of osteoporosis. In all, 60 adult female SD rats were divided randomly into 3 groups of 20 rats each: normal control group (control), sham-operated group (sham), and ovariectomized group (OVX). In 2, 3, 4, 5, and 6 months after surgery, 4 rats were randomized from each group for assays of BMD, IL-6, BALP, and BGP. Then, the rats were sacrificed for the detection of IL-6 and NF-kappabeta expression levels in bone tissue by quantitative real-time RT-PCR analysis. Compared with the sham (0.097 +/- 0.04 g/cm2, 0.097 +/- 0.01 g/cm2, 0.095 +/- 0.07 g/cm2) and control group (0.107 +/- 0.01 g/cm2, 0.103 +/- 0.07 g/cm2, 0.108 +/- 0.06 g/cm2), the BMD of rats in the OVX group was reduced remarkably in 4, 5, and 6 months (0.082 +/- 0.05 g/cm2, 0.073 +/- 0.02 g/cm2, 0.061 +/- 0.05 g/cm2, respectively; P < 0.01); the serum IL-6 level increased significantly from 2 to 6 months after surgery (P < 0.01); and the serum levels of BALP and BGP were greater at 4, 5, and 6 months (P < 0.05). The quantitative real-time RT-PCR analysis demonstrated that IL-6 and NF-kappabeta mRNA levels in OVX group increased in a time-dependent manner. Moreover, the IL-6, NF-kappabeta, BALP, and BGP levels were correlated negatively with the BMD. Meanwhile, a positive correlation was observed between IL-6 and NF-kappabeta. In conclusion, the expression levels of IL-6, NF-kappabeta, and bone formation markers may increase significantly in the osteoporosis rats. These molecules could play a role in the pathogenesis.