Use aluminium-containing biomaterials in otoneurosurgery for reconstitution of bone in contact with cerebrospinal fluid (CSF) also led to cases of encephalopathy and death. We report aluminium (Al) concentrations in the biological fluids of six French patients following use of Al-containing bone cement in otoneurosurgery. In five patients, the mean plasma Al levels (microgram/L) were: 1.20 +/- 0.05 (case 2), 9.20 +/- 0.10 (case 3), 1.00 +/- 0.05 (case 4), 2.80 +/- 0.05 (case 5) and 2.00 +/- 0.05 (case 6). In case 1, Al concentrations were 176 micrograms/L in the postauricular CSF accumulation, 34 micrograms/L in the pontocerebellar angle and 4 and 6 micrograms/L in the lumbar shunt. As a precautionary measure, in the first three cases the biomaterial was removed soon after the intervention, and no increase in plasma or CSF Al was observed. In the other cases, absence of neurobiological symptoms and normal concentrations of Al in plasma led neurosurgeons not to extract this biomaterial. Al assay thus may be considered to be a complementary and at times a decision-generating factor. Care is needed at all stages from sampling through analysis because Al is ubiquitous and factually high results may be clinically misleading. Herein, such considerations are discussed in conjunction with the neurotoxicity of this metal in man. In addition, the authors call for in-depth preliminary trials of these biomaterials in animals prior to introduction on the market.