OBJECTIVE - We evaluated the predictive value of baseline plasma connective tissue growth factor (CTGF) in a prospective study of patients with type 1 diabetes. RESEARCH DESIGN AND METHODS - Subjects were 198 type 1 diabetic patients with established diabetic nephropathy and 188 type 1 diabetic patients with persistent nor- moalbuminuria. Follow-up time was 12.8 years. Prediction of end-stage renal disease (ESRD) and mortality by plasma CTGF was analyzed in conjunction with conventional risk factors. RESULTS - Plasma CTGF was higher in patients with nephropathy than in patients with normoalbuminuria (median 381 [interquartile range 270-630] vs. 235 [168-353] pmol/l). In patients with nephropathy, elevated plasma CTGF was an independent predictor of ESRD (covariate-adjusted hazard ratio [HR] 1.6 [95% CI 1.1-2.5]) and correlated with the rate of decline in glomerular filtration rate (GFR) (cumulative R = 0.46). Area under the receiver operating characteristic curve for prediction of ESRD was 0.72. Plasma CTGF above a cutoff level of 413 pmol/l predicted ESRD with a sensitivity of 73% and a specificity of 63% and was associated with a higher rate of decline in GFR (mean ± SD 5.4 ± 4.9 vs. 3.3 ± 3.5 ml/min per 1.73 m 2 per year). Moreover, in patients with nephrotic range albuminuria (>3 g/day), plasma CTGF was the only predictor of ESRD (covariate-adjusted HR 4.5 [2.0-10.4]). Plasma CTGF was an independent predictor also of overall mortality (covariate-adjusted HR 1.4 [1.1-1.7]). In contrast, in normoalbuminuric patients, plasma CTGF did not correlate with clinical parameters and did not predict outcome. CONCLUSIONS - Plasma CTGF contributes significantly to prediction of ESRD and mortality in patients with type 1 diabetic nephropathy.