OBJECTIVE The mean Hounsfield value of 99.9% ethanol did get down to -190 Hounsfield units (HU), there was a linear correlation between ethanol concentration and Hounsfield values. We aimed to evaluate whether sclerotherapy with estimated ethanol concentration was helpful in improving the success rate for treatment of symptomatic simple hepatic cysts. METHODS Forty-five patients with 52 symptomatic simple hepatic cysts were enrolled in this study. Twenty-one patients (24 cysts, group A) were treated by sclerotherapy without estimated ethanol concentration and 24 patients (28 cysts, group B) with estimated ethanol concentration. The Chi-square test and Mann-Whitney U test were used to compare the difference in characteristics and treatment outcomes of the subjects between these two groups. RESULTS The mean cyst size before and after treatment were 8.4cm and 2.3cm, respectively, in group A, and 8.2cm and 0.8cm, respectively, in group B. There was no significant difference in the initial size of hepatic cysts between the groups. However, the final size was significantly smaller in group B (P=0.022). The mean ethanol exposure time was 18.3minutes in group B, which was less than that in group A (P<0.001). The success rate was significantly higher in group B (96.4%) than in group A (70.8%) (P=0.03). There were no major complications in either group. CONCLUSIONS CT-guided sclerotherapy with estimated ethanol concentration yields better results than those without estimated ethanol concentration in the treatment of symptomatic simple hepatic cysts.