Participant has a history of severe or symptomatic hypertension

Participant has history of heart failure, rhythm disturbance or cardiomyopathy, or obstructive valvular disease

Participant has started taking hypertensive medications within the past 30 days

Participant has a known sensitivity to losartan or history of angioneurotic edema

Study of Losartan in Pediatric Patients With Hypertension (MK-0954-337)