Background: Little is known about the frequencies and types of nonmetabolic complications occurring in type 1 diabetes patients being treated by modern insulin pump therapy (continuous subcutaneous insulin infusion [CSII]), when recorded by standardized questionnaire rather than clinical experience. Subjects and Methods: A self-report questionnaire was completed by successive subjects with type 1 diabetes attending an insulin pump clinic, and those with a duration of CSII of ‡ 6 months were selected for analysis (n = 92). Questions included pump manufacturer, insulin, infusion set type and duration of use, frequency of infusion set and site problems, pump malfunctions, and patient-related problems such as weight change since starting CSII. Results: Median (range) duration of CSII was 3.3 (0.5-32.0) years, and mean -SD duration of infusion set use was 3.2 -0.7 (range 2-6) days. The commonest infusion set problems were kinking (64.1% of subjects) and blockage (54.3%). Blockage was associated with > 3 days of use of infusion sets plus lispro insulin in the pump (relative risk [95% confidence interval], 1.71 [1.03-2.85]; P = 0.07). The commonest infusion site problem was lipohypertrophy (26.1%), which occurred more often in those with long duration of CSII (4.8 [2.38-9.45] vs. 3.0 [1.50-4.25] years; P = 0.01). Pump malfunction had occurred in 48% of subjects (43% in the first year of CSII), with ''no delivery,'' keypad, and battery problems commonly occurring. Although some patients reported weight gain (34%) and some weight loss (15%) on CSII, most patients (51%) reported no change in weight. Conclusions: Pump, infusion set, and infusion site problems remain common with CSII, even with contemporary technology.