A tissue retractor for percutaneous surgery in a patient, comprising: a first portion and a second portion adjacent said first portion, said first and second portions each having a length between a distal end (24, 44) and a proximal end thereof such that said proximal ends are positionable outside the patient and said distal ends are positionable in the patient; a working channel between said first and second portions sized to receive at least one surgical instrument for performance of a surgical procedure, said working channel having an insertion configuration wherein said working channel has a cross-section circumscribed by said first and second portions and an enlarged configuration wherein each of said first and said second portions (22, 42) are laterally separable and pivotable relative to one another to provide said working channel with a cross-section circumscribeable by each of said first and second portions (22, 42) and tissue of the patient between said first and second portions when said working channel is enlarged in the patient; characterized in that a guide member extends between said first portion and said second portion and provides a combined rotational and lateral separation path, at least one of said first portion and said second portion being engageable with said guide member to secure said at least one of said first portion and said second portion at any one of a number of locations along said guide member; and a separation instrument engageable to said proximal ends of said first and second portions, said separation instrument operable to move said at least one of said first and second portions along said guide member; wherein the guide member is curved or arcuate to provide said combined rotational and lateral separation path. a first portion and a second portion adjacent said first portion, said first and second portions each having a length between a distal end (24, 44) and a proximal end thereof such that said proximal ends are positionable outside the patient and said distal ends are positionable in the patient; a working channel between said first and second portions sized to receive at least one surgical instrument for performance of a surgical procedure, said working channel having an insertion configuration wherein said working channel has a cross-section circumscribed by said first and second portions and an enlarged configuration wherein each of said first and said second portions (22, 42) are laterally separable and pivotable relative to one another to provide said working channel with a cross-section circumscribeable by each of said first and second portions (22, 42) and tissue of the patient between said first and second portions when said working channel is enlarged in the patient; characterized in that a guide member extends between said first portion and said second portion and provides a combined rotational and lateral separation path, at least one of said first portion and said second portion being engageable with said guide member to secure said at least one of said first portion and said second portion at any one of a number of locations along said guide member; and a separation instrument engageable to said proximal ends of said first and second portions, said separation instrument operable to move said at least one of said first and second portions along said guide member; wherein the guide member is curved or arcuate to provide said combined rotational and lateral separation path.