Purpose: To record the latest information on control levels of translocations in cultured human lymphocytes. Materials and methods: Control-level data from seven European laboratories that are using fluorescence in situ hybridization (FISH) techniques for retrospective biological dosimetry have been combined in a meta-analysis. After correction for the differing probe combinations used, tests of consistency are performed. The combined data have been used to test for individual variation, systematic variation with age, gender and smoking habits. Results: There is a strong variation of translocation yield with age but no variation was detectable with gender or smoking habits. After correction for age, homogeneity tests showed that about 10% of individuals were outside the 95% confidence limits as opposed to 5% expected. From a total of 385, there is an excess of about 20 individuals most of whom have an unexpectedly high yield of translocations. Conclusions: For retrospective biological dosimetry purposes a generic age-dependent control level can be assumed. No other lifestyle factors such as smoking appear to have a significant effect on translocation yield. © 2005 Taylor & Francis Group Ltd.