Improved health-related quality of life (HRQOL) and reduced activity limitations are prime objectives of migraine therapy, but no data on the effect of preventive treatments on these outcomes are available. We monitored changes in HRQOL using the Short Form 36 (SF-36) and headache-related activity limitations using the Migraine Disability Assessment Score (MIDAS) in 141 consecutive migraine without aura patients on prophylaxis. A total of 102 patients completed the 3-month study. Mean (SD) number of headache days/month dropped from 8.0 (3.7) to 5.0 (2.3) (P < 0.001). Mean monthly consumption of acute drugs reduced from 7.4 (3.5) to 4.4 (3.1) (P < 0.001). MIDAS total score reduced (improved) significantly. All SF-36 scale scores increased (improved), most significantly. This first study to assess prospectively the impact of prophylaxis on HRQOL and daily activities in a large series indicates that migraine prophylaxis has the potential to reduce the global burden of migraine on individuals and society.