Abstract: To provide sufficient seeds for rapidly developing mussel culture,a series of experiments on large scale artificial rearing of mussel spats has been conducted since 1972.In 1973 and 1974,each year we produced over ten million spats in the seven indoor tanks with the total amount of sea water being 20 M³.In 1973,6.69 million spats were harvested from a single concrete tank holding 2.4 M³ of sea water,and in 1974,2.77 million spats were harvested from another concrete tank of the same capacity,giving outputs of 2.29 million and 1.15 million spats per cubic meter of tank water respectively.In 1974,the spats having been transplanted into the sea for some time,2.50 million seed mussels about 2 cm in size were collected and distributed over an area of 10 mow (2/3 hectare) for further growth.Since the artificially reared spats were produced earlier than the natural ones,their growth started earlier too.In the spring of next year,the mussels reached shell sizes of more than 5 cm and were successfully harvested.This early experfence proved that large scale artificial rearing of seed mussels is not only possible but also very promising.