A new coil design for sensitivity‐enhanced ¹³C MR spectroscopy (MRS) of the human brain is presented. The design includes a quadrature transmit/receive head coil optimized for ¹³C MR sensitivity. Loss‐less blocking circuits inside the coil conductors allow this coil to be used inside a homogeneous circularly polarized ¹H B₁ field for ¹H decoupled ¹³C MRS. A quadrature ¹H birdcage coil optimized for minimal local RF heating makes broadband ¹H decoupling in the entire human brain possible at 3 Tesla while remaining well within international safety guidelines for RF absorption. Apart from a substantial increase in sensitivity compared to conventional small linear coils, the quadrature ¹³C coil combined with the quadrature ¹H birdcage coil allows efficient cross polarization (CP) in the brain, resulting in an additional 3.5‐fold sensitivity improvement compared to direct ¹³C measurements without nuclear Overhauser enhancement (NOE) or polarization transfer. Combined with the gain in power efficiency, this setup allows broadband ¹H to ¹³C CP over large areas of the brain. Clear ¹³C resonances from glutamate (Glu), glutamine (Gln), aspartate (Asp), lactate (Lac), and γ‐aminobutyrate (GABA) carbon spins in the human brain demonstrate the quality of ¹³C MR spectra obtained in vivo with this coil setup. Magn Reson Med, 2006. © 2005 Wiley‐Liss, Inc.