Spontaneous hepatic decompensation was observed in 7 of 383 patients coinfected with human immunodeficiency virus (HIV) and hepatitis C virus (HCV) who were receiving treatment with interferon and ribavirin. Multivariate analysis identified the following risk factors: didanosine use (odds ratio [OR], 8.8; 95% confidence interval [CI], 1.2-102.3; P < .02), cirrhosis, (OR, 8.8; 95% CI, 1.2-104.2; P<.02), and elevated total bilirubin level (OR, 7.9; 95% CI, 1.08-93.3; P<.03). Didanosine should thus not be given to patients with cirrhosis, particularly when treatments for HCV and HIV infections have to be administered concomitantly.