Two trials with 15 test items of external quality assessment survey were performed in 2009. The test items were constituted three immunoassay categories, i.e., tumor markers, thyroid hormones and immunoproteins (IgG, IgM, IgA, C3 and C4). Fifteen test items commonly used in clinical laboratories and performed by immunoassay method were surveyed as scheduled. The number of participated laboratory of external quality assessment for Immunoassay Subcommittee were 494 institutions in the first trial survey and 519 institutions in the second survey. All of the fourteen control materials consisted of 12 home-made pooled sera and 2 commercial control sera (Liquimmune(R), Liquid Assayed Immunoassay Control, Microgenics Co, USA) were used for the two trials in 2009 survey. The results are summarized as follows. 1. Laboratories participating in external quality control program of immunoassay were 494 and 519 laboratories and the response rate were 97.6% and 98.3% in 2009. 2. Chemiluminiscence immunoassay autoanalyzers were most commonly used for immunoassay testing in the clinical laboratories for detecting tumor markers and hormones. 3. Stability tests of home-made control materials were performed and confirmed the CV values were in acceptable ranges. 4. Workshops titled "National health examination for tumors" and "Standardization and harmonization of laboratory tests" were held on September 4, 2009 and December 16, 2009 in cooperation with Annual Autumn Academic Conferences of Clinical Laboratory and Quality Control, and Immunoserology Subcommittee, respectively. The quality of the participating laboratories seems to be continuously improved. And, this year, new sixty eight laboratories were participated to our Immunoassay Subcommittee.