The current habit of over-enthusiastic labelling of novel cytokines as ‘interleukins’ has led to considerable confusion for any scientist attempting to follow the recent advances in immunology in Medline, nucleotide/protein databases and patent servers. It seems that the historic argument about whether interferon-γ-inducing factor should be called interleukin (IL)-18, or rather IL-1γ, was only the tip of the iceberg of ambiguity among novel cytokines. A few examples from the ‘over 16s’ might shed more light on this problem, not mentioning the unexpected expansion of IL-1-related cytokines at the very top of the list that has recently been addressed by Sims et al. [1].