IL10, but not IL12 or T regulatory cells in the circulation of newly presenting, pre-treatment head and neck squamous cell carcinoma (HNSCC) patients, has been shown previously to be related to survival over a mean follow-up period of 15 months. Here, we followed the same patients for a longer period to determine whether these associations change. Pre- and post-treatment serum IL10/IL12 and circulating T regs were measured using ELISA and flow cytometry respectively and were correlated with survival after a 33 month average follow-up in a cohort of newly presenting HNSCC patients (n=107), with cancers of the hypopharynx (n=16), larynx (n=36), oral cavity (n=21), oropharynx (n=25), sinonasal (n=4) or unknown origin (n=5). Although the mean survival time of patients with detectable levels of IL10 pre-treatment was lower (40.6 months) than that of those without detectable levels of IL10 (45.6 months), the difference was no longer significant, in contrast to earlier follow-up data. In conclusion, although serum levels of IL10 may be a prognostic indicator for HNSCC patients over the short-term, they become less significant as follow-up time increases.