With astronauts and cosmonauts spending longer periods in space, we must understand and anticipate the effects of the environment on those who live and work in space and on their progeny. Since current launch vehicles restrict payload to low volumes and low masses, we must work within these design restrictions. Two biological experiments, one involving female newts and the other involving the eggs of a small fresh-water fish called revulines, are to be carried aboard the Japanese space flyer unit (SFU) in 1994. The experiment system, named BIO, is implemented on Special Payload Unit (SPLU) of SFU. Experiment are conducted with a service provided for SPLU. BIO consists of two experiment units, a controller, and a power supply. Each experiments, contains an aqua chamber to hold the live specimens. The temperature and gas in the chamber are maintained by a thermo exchanger and gas exchanger. The behavior of the specimens and development of the fertilized eggs are monitored by a CCD camera. The experiment is managed by a microcontroller which collects image and environment data and communicates with the SFU's main control and data management system (CDMS) through the central experiment controller (CEC).The BIO design maximizes performance while using minimal resources. The experiment controller and power supply, which interfaced via the SFU bus, are shared by the two experiment units. Development of the BIO engineering model is completed, and is on the way to manufacturing Proto Flight Model (PFM) for the SFU's first flight in 1994 when it will be launched from Tanegashima by the H-II launcher.