[OBJECTIVE]:To study the effects of environmental factors on the degree of injury and expression of vascular endothelial growth factor (VEGF) and interleukin-1 (IL-1) in cartilage cells of the joint in a rat model of adjuvant arthritis (AA).[METHODS]:SD rats aged 10 months were randomly divided into 4 groups that varied by temperature and humidity housing conditions and induction of AA:a control group,a model group,a cold-damp group,and a hot-damp group.All groups except the control group were induced with AA.After 4 w,VEGF and IL-1 expression in cartilage cells of ankle joints of hind limbs were observed.[RESULTS]:Mean area,optical density,and numbers of VEGF- and IL-1-positive cells in the model group,the cold-damp group,and the hot-damp group were significantly higher than that of the control group (all P＜0.05).Optical density and positive cell numbers in the cold-damp group and the hot-damp group were significantly higher than that of the model group (all P＜0.05).Optical density and positive cell numbers in the hot-damp group were significantly higher than that of the cold-damp group.Bone in the hot-damp and cold-damp groups was severely injured.[CONCLUSION]:Environmental factors such as high humidity combined with either high or low temperature increase the severity of damage and expression of VEGF and IL-1 in cartilage cells of joints in rats induced with AA.