A device (1) for the preparation and administration of liquid substances, particularly antiblastic chemotherapy drugs, comprising: - at least a first connection element (2) connectable to at least a first container (3) containing a first liquid substance (A)； - at least a second connection element (4) connectable to at least one infusion line of a patient； - joining means (5) which define at least one passage channel (7), which is adapted to connect the first connection element (2) to the second connection element (4) in a fluid-operated manner and comprising at least one feeding channel (8) of at least a second liquid substance (B) communicating with the passage channel (7) to obtain at least one mixture (C)； where the joining means (5) comprise removable security means (10, 11, 12) which are interposed between the feeding channel (8) and the second connection element (4) and adapted to temporarily obstruct the passage channel (7).
