An aseptic sampling system comprising: a sampler assembly comprising an outer cap and an interface assembly comprising a shutter, said interface assembly providing an interface between the sampler assembly and a reservoir to be sampled, each assembly (2; 1) comprising a housing (8; 5), each housing (8; 5) defining a separate sterile enclosure for each of the assemblies (2;1); an air lock arranged to provide, in use, the aseptic joining of the sterile enclosures within the sampler and the interface assemblies (2; 1); and a re-sealable liquid connection mechanism (7; 10) positioned to operate within the air lock, wherein: the sampler assembly and the interface assembly are arranged such that, when connected together, they form an outer protective surface comprising the housings (8; 5) of each of the sampler and the interface assemblies (2; 1), the outer protective surface providing a sterile internal enclosure and an air-tight barrier between the outer non-sterile atmosphere and the inner sterile atmosphere, wherein the re-sealable liquid connection mechanism (7; 10) is contained within the sterile internal enclosure and contains at least one liquid connector from each of the sampler and the interface assemblies (2; 1) and is configured such that, in use, at least one of the liquid connectors can move across the sterile internal enclosure and air lock to connect with the other liquid connector of the liquid connection mechanism (7; 10), without contacting any internal surfaces within the air lock, said air lock being provided by said outer cap in the sampler assembly which mates with a slot of said shutter that is slidably accommodated within said housing of the interface assembly such that when said shutter is slid, the outer cap is moved away; and wherein the liquid connection mechanism (7; 10) and its liquid connectors of the respective sampler and interface assemblies is provided by a rotating valve comprising two parts that, when joined, provide a sealing cylindrical surface with at least one internal channel. a sampler assembly comprising an outer cap and an interface assembly comprising a shutter, said interface assembly providing an interface between the sampler assembly and a reservoir to be sampled, each assembly (2; 1) comprising a housing (8; 5), each housing (8; 5) defining a separate sterile enclosure for each of the assemblies (2;1); an air lock arranged to provide, in use, the aseptic joining of the sterile enclosures within the sampler and the interface assemblies (2; 1); and a re-sealable liquid connection mechanism (7; 10) positioned to operate within the air lock, wherein: the sampler assembly and the interface assembly are arranged such that, when connected together, they form an outer protective surface comprising the housings (8; 5) of each of the sampler and the interface assemblies (2; 1), the outer protective surface providing a sterile internal enclosure and an air-tight barrier between the outer non-sterile atmosphere and the inner sterile atmosphere, wherein the re-sealable liquid connection mechanism (7; 10) is contained within the sterile internal enclosure and contains at least one liquid connector from each of the sampler and the interface assemblies (2; 1) and is configured such that, in use, at least one of the liquid connectors can move across the sterile internal enclosure and air lock to connect with the other liquid connector of the liquid connection mechanism (7; 10), without contacting any internal surfaces within the air lock, said air lock being provided by said outer cap in the sampler assembly which mates with a slot of said shutter that is slidably accommodated within said housing of the interface assembly such that when said shutter is slid, the outer cap is moved away; and wherein the liquid connection mechanism (7; 10) and its liquid connectors of the respective sampler and interface assemblies is provided by a rotating valve comprising two parts that, when joined, provide a sealing cylindrical surface with at least one internal channel. the sampler assembly and the interface assembly are arranged such that, when connected together, they form an outer protective surface comprising the housings (8; 5) of each of the sampler and the interface assemblies (2; 1), the outer protective surface providing a sterile internal enclosure and an air-tight barrier between the outer non-sterile atmosphere and the inner sterile atmosphere, wherein the re-sealable liquid connection mechanism (7; 10) is contained within the sterile internal enclosure and contains at least one liquid connector from each of the sampler and the interface assemblies (2; 1) and is configured such that, in use, at least one of the liquid connectors can move across the sterile internal enclosure and air lock to connect with the other liquid connector of the liquid connection mechanism (7; 10), without contacting any internal surfaces within the air lock, said air lock being provided by said outer cap in the sampler assembly which mates with a slot of said shutter that is slidably accommodated within said housing of the interface assembly such that when said shutter is slid, the outer cap is moved away; and wherein the liquid connection mechanism (7; 10) and its liquid connectors of the respective sampler and interface assemblies is provided by a rotating valve comprising two parts that, when joined, provide a sealing cylindrical surface with at least one internal channel.