<p><b>OBJECTIVE</b>To explore the correlation between metabolic tumour volume (MTV) and microvessel density (MVD) and blood-borne metastasis in colorectal carcinoma.</p><p><b>METHODS</b>Thirty-six patients with CRC conformed by pathology underwent PET-CT examination before operation. SUVmax and MTV were obtained by PET VCRA software. The blood vessels were identified with CD34 immunohistochemical staining, and the MVD was recorded. The correlation between SUVmax and MTV with histological differentiation, T stage, MVD and blood-borne metastasis was analyzed.</p><p><b>RESULTS</b>The SUVmax, MTV and MVD in patients with blood-borne metastasis were 5.15 ± 5.41, (22.99 ± 18.63) cm³ and 14.17 ± 3.63, and were 10.65 ± 3.79, (16.95 ± 11.82) cm³ and 11.27 ± 3.69, respectively, in patients with non-blood-borne metastasis. The differences of SUVmax, MTV and MVD between blood-borne metastasis and non-blood-borne metastasis patients were statistically significant (all P > 0.05). Pearson correlation analysis found that there was no linear correlation between SUVmax and MVD, and the SUVmax was not statistically significant between high and low MVD groups (t = 0.919, P = 0.364). But there was a linear correlation between MTV and MVD (r = 0.621, P = 0.000), and the MTV was statistically significant between high and low MVD groups (t = 3.567, P = 0.001). The receiver-operating characteristic curves showed that MTV could be used to predict blood-borne metastasis of CRC, and the best cutoff value for MTV was 14.975 cm³, and the sensitivity, specificity, negative predictive value and positive predictive value were 85.7%, 54.5%, 72.3% and 64.2%, respectively. There were no significant relationships between SUVmax, MTV, MVD, blood-borne metastasis and histological differentiation (P > 0.05). With the increased T stage, the MTV, MVD and the probability of blood-borne metastasis were also increased (all P < 0.05).</p><p><b>CONCLUSIONS</b>There are correlations between MTV and MVD and blood-borne metastasis in CRC. The risk of blood-borne metastasis in patients with MTV > 14.975 cm³ is higher, and needs to take more effective intervention.</p>