OBJECTIVE To investigate the clinical significance of the changes of vascular endothelial growth factor ( VEGF ) and interleukin-6 ( IL-6 ) level in multiple myeloma (MM), solid tumor following bone metastasis. METHODS Thirty- seven MM patients, including 7 in Stage I , 8 in Stage II , 22 in Stage III, 8 solid tumor with bone metastasis patientsly, and 17 healthy controls were enrolled in this study. The serum VEGF and IL-6 levels were determined by ELISA. RESULTS Serum VEGF and IL-6 concentrations in patients with MM and solid tumor were significantly higher than those of the healthy controls (P <0.01 ), and the VEGF level was higher in MM than in solid tumor with bone metastasis. There was significant difference in VEGF and IL-6 levels in various clinical stages of MM. VEGF levels in Stage II were significantly higher than in Stage I (P < 0.05 ) and IL-6 levels in Stage II were significantly higher than in Stage I (P < 0.05). The levels of IL-6 showed great difference according to bone lesion scores (P < 0.05). There was a positive correlation between IL-6 and serum calcium or C-reactive protein( P <0.01) , and there was a positive correlation between VEGF and serum Cr or urinary Bene-Jones protein lambda (P < 0.01 ). The IL-6 levels had significant differences between patients with the normal serum CRP, serum calcium, and beta2-MG and patients with abnormal ones (P < 0.05). VEGF levels showed significant differences between the patients with normal serum Cr, serum calcium Bene-Jones protein lambda, and urinary Bene-Jones protein lambda and patients with abnormal ones (P < 0.05). CONCLUSIONS Serum VEGF and IL-6 levels are helpful to diagnose the clinical stages, and understand bone lesion and serevity of MM.