The aim of the study is to evaluate the efficacy of craniotomy and membranectomy as initial treatment of organized chronic subdural hematoma (OCSH). We retrospectively reviewed a series of 34 consecutive patients suffering from OCSH, diagnosed by magnetic resonance imaging (MRI) or contrast computer tomography (CCT) in order to establish the degree of organization and determine the intrahematomal architecture. The indication to perform a primary enlarged craniotomy as initial treatment for non-liquefied chronic subdural hematoma (CSDH) with multilayer loculations was based on the hematoma MRI appearance--mostly hyperintense in both T1- and T2-weighted images with a hypointense web- or net-like structure within the hematoma cavity. The reason why some hematomas evolve towards a complex and organized architecture remains unclear; the most common aspect to come to light was the "long standing" of the CSDHs which, in our series, had an average interval of 10 weeks between head injury and initial scan. Recurrence was found to have occurred in 2 patients (6% of cases) in the form of acute subdural hematoma. One patient died as the result of an intraventricular and subarachnoid haemorrhage, while 2 patients (6%) suffered an haemorrhagic stroke ipsilateral to the OCSH. Eighty-nine percent of cases had a good recovery, while 11% remained unchanged or worsened. In select cases, based on the MRI appearance, primary enlarged craniotomy seems to be the treatment of choice for achieving a complete recovery and a reduced recurrence rate in OCSH.