This work describes the implementation of two-coil continuous arterial spin labeling (CASL) using a single RF channel and amplifier, avoiding the need for costly additional hardware—namely, a second 1H RF channel and amplifier dedicated to the labeling coil. This is possible in principle, as labeling and imaging RF pulses are never applied simultaneously in the CASL pulse sequence. Simple and inexpensive electronics, together with minor pulse programming modification, were used to create the waveforms (TTL and RF pulses) necessary to drive the two coils. A custom-built RF switch of single-pole double-throw (SPDT) design alternated the output of the RF amplifier between the imaging and labeling coils. Bipolar bias waveforms controlled the switch and also provided active decoupling between the two coils. These waveforms were created from the original TTL waveform, which gated the RF amplifier, using a flip-flop. The method was implemented in a small-bore MRI scanner and enabled good-quality CASL measurements of functional cerebral blood flow changes during whisker electrical stimulation. © 2006 Wiley Periodicals, Inc. Concepts Magn Reson Part B (Magn Reson Engineering) 29B: 145–152, 2006