Objective:To investigate the effects of fetal bovine serum and rat serum on cartilage tissue engineering in vitro,and provide the proper culture method for tissue-engineered cartilage. MethodsThe rat primary chondrocytes were collected and cultured in incubator for 48 hours after centrifugation,and the cell pellets spontaneously formed the cartilage nodules. The cartilage nodules were divided into the fetal bovine serum (FBS) group and rat serum (RS) group. The medium was changed every other day and the cartilage nodules were cultured for continuous 14 days. Then the cartilage tissues were weighed and fixed in 4% paraformaldehyde. The specimens were dehydrated,embedded in paraffin,cut into slices and then stained with hematoxylin-eosin (HE),toluidine blue and safranin O-fast green. The expression levels of type Ⅱ collagen (Col2a1) and type I collagen (Col1a1) were detected by immunofluorescence.  Results:The weight of cartilage tissue in the FBS group was much heavier than that in the RS group,with statistically significant difference (P<0.05). The results of HE staining showed that the tissues exhibited fibrous structures in the RS group but typical cartilage structures in the FBS group. The tissues in the FBS group were obviously stained by toluidine blue and safranin O,while those in the RS group were slightly stained by toluidine blue and strongly stained by fast green,which indicated the cartilage degeneration or non-cartilage tissues. The expression levels of type Ⅱ collagen and type I collagen were detected by immunofluorescence. The type Ⅱ collagen was highly expressed in the FBS group and showed low expression in the RS group. The expression level of type I collagen in the two groups was opposite to that of type Ⅱ collagen,which was high in the RS group and low in the FBS group.  Conclusion:Fetal bovine serum can promote the formation of cartilage tissue,while rat serum can inhibit the formation of cartilage tissue. Fetal bovine serum is more suitable for cartilage tissue engineering in vitro.