Preventive treatment in migraine is associated with poor adherence and persistence. In this observational study, our first aim was to evaluate the perceived effectiveness of onabotulinumtoxinA based on our chronic migraine (CM) patients' treatment experience. The second purpose of this study was to determine the compliance with onabotulinumtoxinA treatment in our cohort. Third, we assessed the reasons for withdrawal from treatment in our CM patients. A total of 245 consecutive patients with CM (40.43 +/- 10.15 years; 214 females, 31 males) were treated with at least one onabotulinumtoxinA. Data were collected by a standardized interview over the telephone. One-hundred and eighty patients were willing to answer questions about: (1) perceived effectiveness of onabotulinumtoxinA based on their treatment experience; (2) the current continuity of the treatment; (3) their current migraine-related disability; and (4) their current medication usage. The mean number of onabotulinumtoxinA cycles of all patients and the participants were 2.58 and 2.90, respectively. Of the 180 participants, 149 patients (82.8%) thought that onabotulinumtoxinA was effective in controlling their headaches. The mean score for perceived effectiveness of onabotulinumtoxinA treatment given by the participants was as 6.94 +/- 2.4 (on a scale from 0 to 10). Of the 245 treated subjects, 31 (12.6%) were treated for 12 months. Compliance rates with onabotulinumtoxinA were very low in our population. However, even CM patients who did not complete five cycles of the treatment showed marked improvement of their current migraine-related disability and reduction of their medication intake as compared to baseline.