Collectin liver 1 (also termed collectin 10 and CL-L1) is a C-type lectin that functions as a pattern recognition molecule (PRM) in the innate immune system1. We have produced antibodies against CL-L1 and have developed a sandwich-type time-resolved immuno-fluorometric assay (TRIFMA) for the measurement of CL-L1 in serum. High oligomeric forms of CL-L1 could be found in plasma and serum. Ontogeny studies revealed that CL-L1 is present a birth at near adult levels. During acute-phase responses we observe an initial decrease in CL-L1 levels followed by a recovery to initial levels. CL-L1 was found to co-purify with MASPs, possibly rendering it a role in complement. CL-L1 showed binding activity towards mannose-TSK beads in a Ca2+-dependent manner. This binding could be inhibited by mannose and glucose, but not by galactose, indicating that CL-L1 binds via its carbohydrate-recognition domain (CRD).