This Presidential Decree, composed of 7 articles and 4 Annexes, establishes minimum measures against bivalve mollusc diseases as indicated in Annex A of Presidential Decree No. 555, 30 December 1992. Under article 2 are defined technical terms, further (arts. 3-6) are indicated the administrative procedures to be followed in the farms where bivalve mollusc are cultivated. All farms rearing bivalve molluscs must be registered by the official service and a record of live bivalve molluscs entering and leaving the farm must be kept. Monitoring and sampling programme will be applied in bivalve mollusc farms in order to observe whether there is an abnormal mortality and a track of the health situation of stocks is kept. Sampling and laboratory testing for the determination of the cause of abnormal mortality of bivalve molluscs shall be also carried out. Annexes A and B concern the Community reference laboratory for diseases of bivalve molluscs and their duties, Annex C the National reference laboratories and a list of diseases and of bivalve mollusc species possibly affected is also given.