That mastoiditis may occur at an early age without evidence of middle ear involvement has been recognized by numerous observers.1Of thirty-five cases of mastoiditis in children, Steinsleger2encountered nine in the range of ages from 7 weeks to 23 months Seven of these nine cases, or 77 per cent, showed no perforation of the tympanic membrane previous to operation. Grulee3states that sinus thrombosis in the new-born is due either to a general infection in the blood stream or to direct extension from the ear, and that it is practically impossible to differentiate it from meningitis when symptoms are present. The following case is an example of the tender age at which these conditions may be found and of the insidious manner in which they may develop. REPORT OF CASE The parents had one other child, aged 6 years, in excellent health. There was no history