The definition of the specific job fitness for individual clinical cases often requires significant detailed investigation by the occupational physician. Such professional commitment is particularly important when biological risks in health care personnel are concerned. In fact, besides correct diagnostic procedures and the specific risk assessment implications, the level of competence of the worker, the safety of patients, work organization, risk perception and health education are also especially relevant. The aim of this paper is to report the case of a young nurse employed in the haematology section of the division of internal medicine, who was in charge of preparing and administering antineoplastic drugs. Risk assessment and a thorough clinical evaluation were performed in order to make a job fitness decision, with specific reference to biological risks. The nurse was suffering from membranous glomerulonephritis and was therefore being treated with various immunosuppressant agents. When she came to occupational physician, risk assessment showed that the preparation and administration of the antineoplastic drugs was not safely performed; the clinical picture showed moderate leukopenia while the kidney disease was functionally controlled. The worker was judged unfit to manipulate antineoplastic or perform activities in divisions at high biological risk. Recommendations were given to follow standard precautions and to follow up the case after cessation of immunosuppressant therapy. The case dealt with a specific biological risk assessment in health care settings and with the need to obtain through knowledge of the clinical state of the subject. Such information is necessary to assess job fitness, also giving recommendations related to employer's and employee's responsibility. The case report also provided the opportunity of underlining the role of the occupational physician in the management of cases of particular clinical relevance and of stressing the necessity of continuing scientific updating in order to reach sound conclusions.