A Research Study Examining the Use of Olanzapine for the Prevention of Migraine

Inclusion Criteria: * Subjects who are male or female between the ages of 18 and 65, inclusive * Subjects who have a history of migraine with or without aura as defined by IHS criteria, for at least one year prior to screening * Subjects who experience between 3 and 10 migraine attacks per month, for the three months preceding screening * Subjects who have no more than 15 headache days per month * Subjects who have been on a stable dose (no clinically significant changes) of all daily medications, for any indication, from 28 days prior to screening through the duration of the trial. * Women who are using, or agree to use for the duration of the study, a medically acceptable form of contraception (as determined by the investigator), if female of childbearing potential. * Subjects who are able to understand and comply with all study requirements * Subjects who provide written informed consent prior to any study procedures being performed. Exclusion Criteria: * Women who are pregnant or lactating * Subjects with an abnormal ECG that, in the investigators opinion, would expose them to increased risk of adverse events or interfere with study drug and/or analysis of efficacy/tolerability (subjects with QTC interval greater than 450ms will be excluded) * Subjects currently taking, or have taken within the thirty days prior to screening, any neuroleptics \> 1 day per week (such as Geodon, Zyprexa, Compazine, Phenergan, Seroquel and other drugs in the same class) * Subjects currently taking or have taken within 4-weeks prior to screening any medication for the prevention of migraine * Subjects who have failed more than two adequate trials of migraine prophylaxis, as determined by investigator * Subjects who experience significant orthostatic hypotension, as determined by the investigator * Subjects who, in the investigators opinion, have a history or have evidence of a medical condition that would expose them to an increased risk of a significant adverse event or would interfere with the assessments of efficacy and tolerability during this trial * Subjects who, in the investigators opinion, have a history or have evidence of a psychiatric condition that would expose them to an increased risk of a significant adverse event or would interfere with the assessments of efficacy and tolerability during this trial. * Subjects who have participated in an investigational drug trial in the 30 days prior to the screening visit