Abstract Epilepsy surgery is a viable therapy option especially for patients with a well-defined focus. A parameter for estimation of good surgical outcome, acquired during presurgical workup using MEG dipole localizations, is presented. MEG data of 22 surgically treated epilepsy patients were analyzed retrospectively. Data had been recorded during presurgical workup using a 74-channel dual-unit biomagnetometer (Magnes II, 4D-Neuroimaging, CA, USA). Individual MRI was co-registered. Data were inspected visually and analysed using single dipole localization in a BEM volume conductor model (boundary element method), using an automated process (Curry 4.6, Compumedics Neuroscan, El Paso, TX, USA). Resulting localizations were inserted additively into a 3D-volume. This analysis resulted in continuous dipole frequency volumes with local maxima at loci designated by an increased amount of dipole localizations. The volume of the smallest hull, enveloping loci with dipole localization amounts above the 99.9th percentile, was calculated and normalized to the total number of localizations. The resulting convex hull volume (“chv”) values were then compared to surgery outcome. A threshold for good outcome was estimated by calculating the minimum parameter value of patients with Engel outcomes 3 and 4. Lowest chv value of patients with Engel outcomes 3 and 4 was 1.22 mm3/localization. Using this value as threshold for good outcome, 11 patients with outcomes 1 and 2 were under this threshold. The 6 patients with outcomes 3 and 4 yielded results above the threshold, as well as 6 patients with outcomes 1 and 2. This distribution was found to be significant (p