Objective: To compare the complications of peripherally inserted central catheters (PICC) by a modified Seldinger technique under ultrasound guidance or the conventional (peel-away cannula) technique. Methods: From February to December of 2010, cancer patients who received PICC at the Department of Chemotherapy in Jiangsu Cancer Hospital were recruited into this study, and designated UPICC if their PICC lines were inserted under ultrasound guidance, otherwise CPICC if were performed by peel-away cannula technique. The rates of successful placement, hemorrhage around the insertion area, phlebitis, comfort of the insertion arm, infection and thrombus related to catheterization were analyzed and compared on days 1, 5 and 6 after PICC and thereafter. Results: A total of 180 cancer patients were recruited, 90 in each group. The rates of successful catheter placement between two groups differed with statistical significance (P <0.05), favoring UPICC. More phlebitis and finger swelling were detected in the CPICC group (P <0.05). From day 6 to the date the catheter was removed and thereafter, more venous thrombosis and a higher rate of discomfort of insertion arms were also observed in the CPICC group. Conclusion: Compared with CPICC, UPICC could improve the rate of successful insertion, reduce catheter related complications and increase comfort of the involved arm, thus deserving to be further investigated in randomized clinical studies.