The preparation methylmethacrylate (MMA) an organic solvent which is employed inter alii in the production of prostheses, is regarded as neurotoxic. With the object of illustrating to what extent dental technicians have symptoms compatible with organic dementia as compared with a control group, a cross-sectional questionnaire investigation was undertaken in a population consisting of 256 dental technicians and 160 opticians, all of whom were professionally active. The percentage replies for the two group were 88 and 85 respectively. The two groups do not differ from one another as regards background variables with the exception of age and adjustments are made for this in the analysis. The results demonstrate that there is a statistically higher prevalence of the majority of acute and also chronic symptoms among dental technicians than among opticians. The symptom pattern and the presence of information and selection bias are discussed and it is concluded that this investigation confirms the hypothesis that symptoms compatible with organic dementia are commoner among dental technicians. The results raise the suspicion that MMA may cause acute and chronic damage to the central nervous system, even after very slight exposure. Revision of the occupational environment of dental technicians, including the current hygienic limits for MMA, is recommended.