Objectives: Early assessment of hepatocellular carcinoma (HCC) response during sorafenib (SO) treatment is challenging, since tumor necrosis, extension and radiological appearance can be inhomogeneous. We evaluated the predictive value of different imaging criteria - such as Response Evaluation Criteria in Solid Tumors (RECIST) 1.1, European Association for the Study of the Liver (EASL), modified RECIST (mRECIST), tumor density and volume variations - in the early follow-up of SO treatment. Methods: The study included 22 patients. CT images from baseline and 2 months were reviewed to assess response according to RECIST 1.1, mRECIST, EASL, Choi's criteria (decreased tumor density by ≥15%) and arterial-enhancing tumor volume ratio; α-fetoprotein (AFP) variations were expressed as AFP ratio. Results: The response criteria and volume measurements were reproducible (k > 0.80). The overall disease control rate was 40.9% by EASL and mRECIST, and 27.3% by RECIST 1.1; a ≥15% decrease in tumor density was observed in 9 patients (40.9%). The mean volume ratio was 1.73 ± 2.12, the mean AFP ratio 14 ± 37. The 1-year survival rate was 65.9%. Volume ratio was the only predictive factor for survival, with 1-year cumulative survival rates of 90% for volume ratios ≤1.1 and of 45.4% for volume ratios >1.1 (p = 0.04). Conclusions: Tumor volume measurements are reproducible and might provide an early predictive marker of response in HCC patients treated with SO.