The aim of this work was to investigate the possibility of the transmitter power reduction in multireceiver infrared biotelemetry systems when the transmitter is worn by ambulatory patient. Energy that flows from a mobile emitter to a stationary receiver undergoes several transformations. It is transformed from modulated electrical to optical form at the emitter. That optical energy falls on the large reflective surface and diffuse reflected part of it, together with background radiation, irradiates infrared sensor that transforms it back to electrical form. Receiver preamplifier amplifies the sensor's photocurrent adding its noise. The generated electrical signal is processed in central unit of the multireceiver system. Optimisation of each step of energy flow and transformation is carried out through theoretical analysis and experimentally verified. Pulse-position modulation was found as the most appropriate choice for obtaining high impulse power with low average consumption. Optimal infrared emitting diode pulse current for highest power efficiency was calculated. pin photodiode was chosen as a detector of weak diffuse radiation. The performance of the photodiode in current mode was found as optimal from sensitivity and bandwidth point of view. Two types of receiver preamplifiers, voltage and transimpedance amplifier were described and their features were characterised. The transimpedance amplifier gives higher frequency range and better sensitivity. Both amplifiers have input noise composed of two components: the white noise and the noise with spectral density proportional to the product of frequency and input capacitance. The dominant noise is detector's shot noise arising from the background light. The signal to noise ratio of the preamplifier is improved using multiple detectors with one preamplifier or summing outputs of more preamplifiers. Central unit in multireceiver space diversity system performs selection or equal-gain diversity combining technique. Reduction of transmitter power is accomplished through decreasing the covering area of each receiver in multireceiver system. The presented results give rules for designing and objective evaluation of low-power infrared biotelemetry systems. They are applicable in development of similar indoor infrared communication systems and their comparison to RF systems.