Balloon catheter, guide catheter and method for dilating openings in paranasal sinuses. A non-removable guide member (e.g., guidewire) extends from the distal end of the balloon catheter. The non-removable guide member initially passes through the opening of the paranasal sinus and is followed by the catheter body on which the balloon is mounted. The balloon is then inflated causing dilation of the opening of the paranasal sinus. In some embodiments, the non-removable guide member may be shapeable so that the operator may place the non-removable guide member in a desired shape prior to insertion of the balloon catheter. In some embodiments, the length of the non-removable guide member may be adjustable such that the operator may adjust the length of the non-removable guide member prior to insertion of the balloon catheter.