We evaluated and compared the diagnostic accuracy (DA) of apparent diffusion coefficient (ADC) values with that of lesion-to-liver ADC ratios in the characterization of solid focal liver lesions (FLLs). This prospective study was approved by the Institutional Human Ethics Board, after waiving written informed consent. Diffusion-weighted imaging and other routine magnetic resonance imaging were performed on 142 consecutive patients with suspected liver disease. The mean ADC values and lesion-to-liver ADC ratios were compared between benign and malignant solid FLLs. Receiver operating characteristic analysis was performed. The study participants included 46 patients (28 men, 18 women; mean age, 52.5 years) with 57 solid FLLs (32 malignant and 25 benign FLLs). The mean ADC values and ADC ratios of benign solid FLLs were significantly higher than those of malignant lesions (P < 0.01). The difference between the area under the receiver operating characteristic curve of the ADC values (0.699) and ADC ratios (0.752) was not significant. Our study suggests that the DA of the ADC ratio is not significantly higher than that of ADC in characterizing solid FLLs.