Increase modal size for Twitter Bootstrap

I was having the exact same problem, you can try:

.modal-body {
    max-height: 800px;
}

If you notice the scroll-bars appear only on the body section of the modal dialog, this means that the max-height of only the body needs to be adjusted.

You need to make sure that it is on the #myModal .modal-body element not just #myModal (Seen a few people make this mistake) and you may also want to accomodate for the height change by changing the modals margins.

in Bootstrap 3:

.modal-dialog{
  width:whatever
}