Purpose of the study: determination of a systematised procedure for medical follow-up of beryllium-exposed workers. Method: a medical follow-up of workers from a factory machining beryllium (Be) either plain or as an alloy started in 2001. Be Lymphocyte Proliferation Tests (LPT) were performed for screening Be sensitisation and were calculated again according to 1142-2001 speciation of the American Department Of Energy. A working group included occupational physicians, specialists in occupational prevention and biologists and established based on a review of medical literature an algorithm for medical folllow-up of workers. This algorithm determines how to handle medically such workers and is mostly based upon Be LPT results. Results: 14 workers were followed for 6 years at the most. Abnormal (positive or border-line) tests were noticed in 4 of them. These tests became negative within 3 to 18 months in 3 of them, in parallel with Be working decrease and with strengthening of preventive measures. Neither respiratory, nor radiological, nor functional abnormal symptom occurred in the 4th worker that could evoke an out coming chronic berylliosis. Discussion and conclusion: This shows how necessary it is to standardise Be LPT method and results and how important it is to establish guidelines for a long-term follow-up of workers who may be exposed to Be and to strengthen preventive measures. Key words: beryllium, sensitisation, occupational exposure, prevention, Lymphocyte Proliferation Test