Mathematical modeling suggests an impractical number of radiofrequency ablation (RFA) zones needed in order to ablate a medium-large hepatic tumor. However, overlapping RFA zones may increase the necrotic diameter disproportionately to that deduced from single ablation alone. Objectives: To compare the necrotic diameter in single (Group1), dual overlapping (Group2) and dual non-overlapping (Group3) ablation. Methods: Single (n=5) and dual (overlapping n=18; non-overlapping n=6) ablation zones were created in ex vivo porcine livers using Cool-tip RFA electrodes. Necrotic diameter was measured at the midpoint (MaxD) of the single and the two distinct RFA zones of the dual ablation groups and compared with the necrotic diameter at the tip of the second ablation (MaxD-O), corresponding to the point of overlap in Group2. The RFA electrode was withdrawn 2.5 and 4.1 cm before re-ablating for Group2 and Group3, respectively. Results: Despite no difference in end-RFA temperature between 3 groups (Group1=75.6+7.4Cvs.Group2=73.9+7.3Cvs.Group3=74.8+4.8C; p=0.873), MaxD was significantly greater (p=0.011) in Group2 (4.1+0.7cm) as compared to Group1 (3.3+0.6cm) and Group3 (3.3+0.4cm), with no difference between Group1 and Group3(p=1.00). Further proof of synergism between two overlapping ablations is that the MaxD-O in Group2(4.3+0.6cm) was larger than MaxD of Group1 (p=0.042) and Group3 (p=0.028), and was similar to MaxD of Group2 (p=1.00). Conclusions: Overlapping two RFA zones results in incremental increase in necrotic diameter compared to single and dual non-overlapping ablation. This may explain the discrepancy in the number of ablation zones needed between clinical and mathematical modeling studies. Background: Hepatocellular carcinoma (HCC) is the fourth most common cancer worldwide, main etiological factors being chronic infections with hepatitis B and C viruses. The present study was undertaken to evaluate the association of glutathione-S-transferase (GST) T1 and M1 null genotypes and microsomal epoxide hydrolas e(mEPHX) polymorphisms with hepatitis virus related HCC risk in Indian population. Subjects and Methods: Three groups of subjects were considered viz. control (n=169), chronic viral hepatitis (n=174) and HCC (n=63). PCR-RFLP was used for this polymorphic study. Genotype distributions between categories were compared using the 2 test; odds ratios (ORs) and 95% CI were calculated to express the relative risk. Results: Presence of GSTM1 null genotype significantly (p<0.05) decreased the risk for HCC development among chronic viral hepatitis subjects. However, GSTT1 null genotype was associated with an increased risk for HCC by 2.23 and 1.42 times among control and hepatitis subjects respectively. In case of mEPHX, Tyr113His and His113His genotypes significantly (p< 0.05) reduced the risk of HCC development in both viral hepatitis and control subjects. In case of mEPHX exon 4 genotypes, Arg139Arg imposed an approximate 2 fold risk for HCC development in the two groups. Combination of heterozygous mutant genotypes at mEPHX exons 3 & 4 also imposed around 2 fold risk (non-significant) for HCC. Conclusions: Polymorphic forms of GST and mEPHX share an association with viral related HCC risk in Indian population and should be further evaluated as the candidate genes to determine individual susceptibility for viral related HCC. 