A radiolucent iliac crest support frame for supporting the iliac crest of a person and maintaining the person's spine in a substantially straight horizontal position is disclosed. The support frame comprises a radiolucent sheet, means for causing the sheet to grip the horizontal surface when the sheet is placed on the surface, means for supporting the iliac crest of a person above the sheet and for maintaining the person's spine in a substantially straight horizontal position, and means for adjustably attaching the supporting means to the radiolucent sheet. The supporting means preferably are two oblong radiolucent pillows adjustably attached to the sheet by means of fastener pads and strips whereby the position of the pillows can be adjusted to accommodate patients of different sizes.