Two cases of frontal and ethmoidal pyoceIe converted into a common cavity, with one side communicating with another, and exposing dura mater, are reported. Without any intracranial complications, they were healed by Kilian's radical operation. Case 1: A woman aged 59; the size of cavity was 9.5×5.0cm. Case 2: A man aged 29; the size of cavity was 8.5×4.7cm.
