The PROMO (preference for once monthly bisphosphonate) Study, conducted in seven hospital centres in Croatia between June 2007 and June 2008, was designed to analyse patient preference for weekly and monthly bisphosphonates in everyday clinical practice where the significant proportion of patients are not completely satisfied with the current osteoporosis treatment. Eligible participants were women with postmenopausal osteoporosis taking weekly bisphosphonates for the last 6 months. Those who agreed to be enrolled were transferred from weekly to monthly ibandronate for the next 6 months. There was no washout period between the two treatment regimens. At the baseline, patients expressed their satisfaction with the weekly treatment. At the end of the study, all patients were asked to complete the five-question survey specially designed for this study. Study population comprised 258 participants. Among 248 patients who completed the study, 244 (98.4%) declared their preference for one of the regimens or they had no preference. Once-monthly regimen was preferred by 231 patients (94.7%), whereas once-weekly regimen was preferred by five patients (2.0%). Eight patients (3.3%) indicated no preference. Furthermore, 93.0% of patients thought that monthly dosing was more convenient. Compared to weekly regimen, monthly dosing was associated with significantly higher satisfaction with the treatment and with significantly less adverse events. In line with these data, 85.9% of patients stated improved quality of life with monthly ibandronate. In summary, the PROMO Study demonstrated strong patient preference for monthly over weekly dosing which is expected to improve suboptimal adherence to weekly bisphosphonates.