This paper reports on design and development of a reliable, single-chip, multichannel wireless biotelemetry microsystem intended for extracellular neural recording from awake, and behaving small animal models. The system requirements for reliable neural recording are identified and the inherently conflicting requirements of low power and reliability are addressed at architectural and circuit levels. The 2.85 × 3.84 mm², mixed-signal ASIC is fabricated in a 0.5 μm 2P3M n-well standard CMOS process; and integrates a low-noise front-end, programmable digital controller, an RF modulator, and an RF power amplifier at the ISM band of 433 MHz on a single-chip. The microsystem, incorporating the ASIC, features 9-channel, is programmable, weighs 2.2 g (including batteries) and has dimensions of 2.2 × 1.1 × 0.5 cm³. The transmitter consumes 5 mW and has a measured input referred voltage noise of 4.58 μV rms, 6.20 μV rms, and 7.81 μV rms at transmission distances of 3 m, 10 m, and 20 m, respectively. The measured inter-channel crosstalk is less than 3.5% and battery life is about an hour. The presented biotelemetry system has been successfully used in two in-vivo neural recording experiments: i) from the antennas of a freely roaming South-American cockroach, and ii) from the hippocampus of an awake and mobile rat.