Background: The implication and clinical significance of low-level viremia (LLV) in HIV patients are still not clear. This study aimed to characterize the clinical outcomes and to evaluate whether LLV could predict future virological failure in a well-defined cohort of HIV-infected Omani patients attending a large HIV clinic. Methods: Patients on regular antiretroviral therapy (ART) for at least 12 months, and had at least 2 HIV RNA measurements 1 year after starting ART, were prospectively enrolled in a cohort study. LLV was defined as plasma HIV RNA between 50-200 copies/mL that persists after at least 2 consecutive measurements after 12 months of ART. Multivariate Cox proportional hazards regression model was used to measure the association among virological failure, LLV and potential predictors. Results: After 12 months of starting ART, 60 patients (40%) had undetectable viral load (UVL) 50 copies/mL, while 37 patients (24%) had LLV and 53 patients (35%) had primary virological failure > 200 copies/mL. The incidence rates of subsequent secondary virological failure for UVL and LLV groups, were 3 and 7 cases per 1000 patient-months, respectively. Compared to UVL group, LLV group had increased risk of subsequent secondary virological failure with hazard ratio of (4.437 [95% CI, 1.26-15.55]; p = 0.02). Age, duration of HIV infection, pretreatment HIV RNA level, pretreatment CD4+ cell count, and ART adherent were associated with subsequent secondary virological failure. Conclusion: Collectively, Omani HIV patients with LLV were at a higher risk for HIV virological failure, and should be monitored closely. Further studies are need to assess whether ART modification in LLV patients would lower the risk of virological failure.