A prospective cohort study was undertaken to describe the natural history of the cubital fossa peripherally inserted central catheter (PICC), determine which factors influenced the hazard of complication and develop a standard methodology for evaluation of a PICC service. A total of 4349 patient days of PICC observation were analysed using survival analysis techniques. The median time to PICC removal for a complication was 60 days. The most common complications were phlebitis, malposition and tip migration. Complications usually occurred during the first week. There was only one episode of line-related sepsis. Size 3 French gauge catheters had a complication rate of 7.3 per 1000 line days compared to 14.2 for 4 French catheters (hazard rate 1.26 90% CI 1.02 to 1.55). PICCs requiring two or more attempts at insertion were more likely to develop complications than those inserted at the first attempt: 20 per 1000 line days vs 10.5 but the confidence intervals were wide (hazard rate 1.91, 90% CI 0.90 to 4.05). Operator (amongst the four experienced operators who inserted all PICCs), arm of placement, or medial or lateral placement in the cubital fossa did not influence PICC survival.