BACKGROUND Biofilms often colonize catheters and contribute to catheter-related septicemia. However, predictors of catheter colonization by biofilms remain poorly defined. The aim of this study was to evaluate clinical factors that may be associated with biofilm colonization of catheters. METHODS A total of 54 isolates colonizing the peripheral intravascular catheters (IVCs) were studied and their biofilm production ability was analyzed by the tube method and antimicrobial susceptibility was also done. A detailed clinical history and examination was done of each subject to know age, sex, duration of use of IVCs, site of IVCs, swelling/purulence around the IVCs, number of attempts to install the catheter, and duration of hospital stay. RESULTS 44 (81.4%) out of 54 isolates colonizing the catheters showed biofilm formation. Biofilm formations were significantly associated with duration of hospital stay of more than 7 days [odds ratio (OR) = 6.6; 95% confidence interval (CI) = 1.3-34; P value (P) = 0.02], multiple attempts to install the catheter (OR=7; CI=1.5-31.8; P=0.01), and multidrug resistance (OR=9.5; CI=1.8 - 51.1: P=0.008). Klebsiella pneumoniae and Candida spp. comprised most of the biofilm-producing isolates. The overall susceptibility to antimicrobials was low among biofilm-producing compared to nonbiofilm-producing microbes. CONCLUSIONS The results of this study suggest that evaluation of predictors of biofilm production is important in order to understand, prevent or manage biofilm colonization of IVCs.