A guide tube for a minimally invasive surgical system has a single channel that accepts two or more surgical instruments. The channel has two or more bores, and a body segment of each instrument extends through a unique one of the bores. A slot connects two of the bores along the length of the channel. A distal component of one of the instruments is larger than the instrument's bore, and so the component slides through the slot, and in some aspects through some or all of the other bore, as the instrument is inserted through the guide tube. After the instrument has been inserted, a second instrument can then be inserted through the other bore.