A system for treating a disease or disorder of the ear, nose or throat of a human or animal subject, said system comprising: a guide catheter (40a-40f) that is insertable through a nostril of the subject, said guide catheter (40a-40f) having a rigid shaft, a proximal opening, a distal opening and a lumen extending between the proximal opening and the distal opening; and a dilation catheter that is insertable through the lumen of the guide catheter (40a-40f), said dilation catheter having a proximal portion (12prox) and a distal portion (12dist), wherein said dilation catheter comprises a shaft and an expandable dilator, said expandable dilator comprising a balloon that is positionable within an ostium of a paranasal sinus while in an unexpanded state and thereafter expandable to an expanded state to dilate said ostium; the distal portion (12dist) of the dilation catheter being advanceable out of the distal opening of the guide catheter (40a-40f); characterized in that: said proximal portion (12prox) is rigid and said distal portion (12dist) is flexible; the overall length of the dilation catheter shaft is from 15cm to 25cm, the length of said proximal portion is from 10cm to 15cm, the length of said distal portion (12dist) is from 5cm to 10cm; the dilation catheter being sized relative to the guide catheter (40a-40f) so that, when the distal portion (12dist) of the dilation catheter is advanced out of the distal opening of the guide catheter and the balloon is being used to dilate an ostium of a paranasal sinus, only the rigid proximal portion (12prox) or some portion thereof will extend out of the proximal opening of the guide catheter (40a-40f); and said system further comprises a handle (42, 42a, 42b, 42c, 48) that is attached to the guide catheter (40a-40f) at the proximal opening of the guide catheter (40a-40f), such that the dilation catheter is insertable through the handle (42, 42a, 42b, 42c, 48) into the lumen of the guide catheter (40a-40f), wherein said dilation catheter has at least one shaft marking (24, 26) being arranged on said proximal portion (12prox) for indicating the longitudinal position of said dilation catheter within said guide catheter (40a-40f). a guide catheter (40a-40f) that is insertable through a nostril of the subject, said guide catheter (40a-40f) having a rigid shaft, a proximal opening, a distal opening and a lumen extending between the proximal opening and the distal opening; and a dilation catheter that is insertable through the lumen of the guide catheter (40a-40f), said dilation catheter having a proximal portion (12prox) and a distal portion (12dist), wherein said dilation catheter comprises a shaft and an expandable dilator, said expandable dilator comprising a balloon that is positionable within an ostium of a paranasal sinus while in an unexpanded state and thereafter expandable to an expanded state to dilate said ostium; the distal portion (12dist) of the dilation catheter being advanceable out of the distal opening of the guide catheter (40a-40f); characterized in that: said proximal portion (12prox) is rigid and said distal portion (12dist) is flexible; the overall length of the dilation catheter shaft is from 15cm to 25cm, the length of said proximal portion is from 10cm to 15cm, the length of said distal portion (12dist) is from 5cm to 10cm; the dilation catheter being sized relative to the guide catheter (40a-40f) so that, when the distal portion (12dist) of the dilation catheter is advanced out of the distal opening of the guide catheter and the balloon is being used to dilate an ostium of a paranasal sinus, only the rigid proximal portion (12prox) or some portion thereof will extend out of the proximal opening of the guide catheter (40a-40f); and said system further comprises a handle (42, 42a, 42b, 42c, 48) that is attached to the guide catheter (40a-40f) at the proximal opening of the guide catheter (40a-40f), such that the dilation catheter is insertable through the handle (42, 42a, 42b, 42c, 48) into the lumen of the guide catheter (40a-40f), said proximal portion (12prox) is rigid and said distal portion (12dist) is flexible; the overall length of the dilation catheter shaft is from 15cm to 25cm, the length of said proximal portion is from 10cm to 15cm, the length of said distal portion (12dist) is from 5cm to 10cm; the dilation catheter being sized relative to the guide catheter (40a-40f) so that, when the distal portion (12dist) of the dilation catheter is advanced out of the distal opening of the guide catheter and the balloon is being used to dilate an ostium of a paranasal sinus, only the rigid proximal portion (12prox) or some portion thereof will extend out of the proximal opening of the guide catheter (40a-40f); and said system further comprises a handle (42, 42a, 42b, 42c, 48) that is attached to the guide catheter (40a-40f) at the proximal opening of the guide catheter (40a-40f), such that the dilation catheter is insertable through the handle (42, 42a, 42b, 42c, 48) into the lumen of the guide catheter (40a-40f),