Kinetics of hepatitis C virus (HCV) during pegylated interferon (PEG-IFN) and early monitoring of viral decline were recently described to predict treatment outcomes and in turn reduce the course of treatment, adverse effects and cost. However, there is limited (if any) information on the viral dynamics of HCV-4. Our aim is to follow the HCV-RNA kinetics during PEG-IFN alpha 2a and ribavirin therapy and the best time for predicting sustained viral response (SVR) in genotype-4 patients. Serum HCV-RNA levels before initial dosing (baseline level) and at 24 h, week 1, week 4, week 12, week 24, week 48 and week 72 were assessed in 84 HCV genotype-4 patients treated weekly by PEG-IFN alpha 2a and daily ribavirin. At the end of treatment, out of the 84 treated patients, 19 (22.6%) were non-responders while 65 (77%) showed end-of-treatment response (ETR). However, 8 patients relapsed (9.5%), thus the SVR was observed in 57 patients (67.9%). Younger patients were more likely to attain SVR, where the odds of SVR increased by a factor of 0.94 for each year increase in age (95% CI: 0.90-0.99, P = 0.019). Although a significant negative correlation between stage of fibrosis and rate of viral decline at weeks 1 and 4 (P < 0.005 and 0.001, respectively) was seen, neither fibrosis stage (chi(2) = 3.4882, P > 0.1) nor grade of inflammation (chi(2) = 0.0057, P > 0.1) significantly predicted response to treatment. Non-responders had no or only a limited decline at week 1 and week 4, whereas sustained virological responders had a significant decline at both week 1 and week 4. Area under the (receiver operating characteristic) curve (AUC) revealed that week 12 is better than any other time point in predicting the SVR (AUC = 0.97; 95% CI: 0.94-1.01), (sensitivity 98.3%; 95% CI: 90.7-99.9), (specificity 88.5%; 95% CI: 71.0-96.0), positive predictive value of 94.9% and negative predictive value of 95.8%. A drop of more than 1.17 log viral load at week 1 and viral clearance or decline > 3 log were considered as the earliest predictors of SVR. In genotype-4 patients, while failure to achieve an EVR at week 12 predicts non-response, an RVR at week1 and week 4 98% guaranteed SVR. These findings further re-enforce the value of week 12 in the course of IFN treatment. Genotype-4 patients who show significant viral clearance (> 1.17log viral load) by the first week of treatment and viral clearance > 3log by week 4 are expected to show SVR and should therefore be assigned to a shorter drug regimen lasting for 24 weeks. Those unfortunate cases who do not achieve viral clearance by week 1 or week 4 should not be deprived from the treatment but rather given more time till week 12 before being classified as non-responders.