A masking package to mask syringes or vials in a blind drugs trial comprises an opaque housing formed of first and second housings 104/304, 102/302 and an adaptor 122/322. The adaptor 122/322 is fixed, in use, to a syringe or vial and an inner surface of the first housing 104/304. The second housing 102/302 can move relative to the first housing 104/304. The housings 104/304, 102/302 may comprise open and closed ends, the closed end of the first housing 104/304 having an orifice 123/323 for receiving a syringe needle. The housings 104/304, 102/302 may be cylindrical. The first housing 104/304 may have first and section sections with a shoulder between them. The adaptor 122/322 may close the open end of the first housing 104/304. One of the housings 104/304, 102/302 may be slidable within the other. The second housing 102/302 may have an inner surface (144 fig 4a) which engages with a plunger of a syringe. The adaptor 122/322 may comprise two portions. The first housing 104/304 may include a window (108 fig 5a) and/or one of more flanges (110 fig 5a).
