Objective To investigate the feasibil ity of alendronate (ALN) in treating osteoarthritis (OA) by observing the effects of ALN on interleukin 1β (IL-1β) induced chondrocytes of rat in vitro. Methods The chondrocytes of knee articular surface from 15 SD rats (1-month-old, female or male, weighing 100-150 g) were cultured. The chondrocytes were observed by inverted phase contrast microscope and identified by toluidine blue staining and HE staining. The third passage chondrocytes were divided into 3 groups: the chondrocytes were cultured with DMEM for 5 days in group A, with 10 ng/mL IL-1β for 2 days and with DMEM for 3 days in group B, and with 10 ng/mL IL-1β for 2 days and with 1 × 10-6 mol/L ALN for 3 days in group C. Immunocytochemistry and real-time PCR were performed to determine the expression levels of collagen type II (Col II), matrix metalloproteinase 13 (MMP-13), and β-catenin. Results Toluidine blue staining proved that the cultured cells were chondrocytes. The integrated absorbency (IA) value of Col II in group C (10.290 7 ± 0.499 2) was lower than that in group A (15.377 0 ± 0.571 8) and higher than that in group B (5.463 2 ± 0.450 4), showing significant differences (P lt; 0.05). The IA value of MMP-13 in group C (3.068 6 ± 0.205 6) was significantly lower than that in group B (6.998 1 ± 0.329 7, P lt; 0.05), but there was no significant differenc when compared with group A (2.777 5 ± 0.199 6, P gt; 0.05). The IA value of β-catenin in group C (6.611 7 ± 0.381 8) was lower than that in group B (11.799 9 ± 0.348 7) and higher than that in group A (4.390 3 ± 0.551 9), showing significant differences (P lt; 0.05). The mRNA expression of Col II in group C was significantly higher than those in groups A and B (P lt; 0.05), the mRNA expression of MMP-13 in group C was significantly lower than that in group B (P lt; 0.05) but there was no significant difference when compared with group A (P gt; 0.05). The mRNA expression of β-catenin in group C was significantly lower than that in group B (P lt; 0.05) and higher than that in group A (P lt; 0.05). Conclusion ALN can protect rat chondrocyte from OA induced by IL-1β in vitro possibly by upregulating Col II and inhibiting the expression of MMP-13 and β-catenin in the chondrocytes.