Background. Few cases of cutaneous lymphocytic hyperplasia secondary to vaccin ation have been published, although such lesions are not rare. Patients and meth ods. We report a series of 10 cases registered between 1993 and 2003. Results. M ean age was 25. The clinical aspect was solitary or multiple subcutaneous nodule s, located on the arm, developing after a delay of 1 to 18 months after vaccinat ion. Histologic examination showed a lymphocytic infiltration of the subcutaneou s fat, with diffuse and/or follicular pattern, without nuclear atypia, the morph ological and immunohistochemical analysis of which revealed the benigh nature. I n all cases, there was fibrosis and granuloma composed of lymphocytes, plasma ce lls, eosinophils and macrophages with basophilic cytoplasm. Morin stain showed i ntralesional aluminium in the 6 investigated cases. Evolution was always benign, with no relapse following exeresis. Discussion. Cutaneous lymphocytic hyperplas ia secondary to vaccination has to be suspected in a young patient with subcutan eous nodules appearing at a vaccination site. Evidence of aluminium in the lesio ns supports the diagnosis and the hypothesis that aluminium in the vaccine excip ient might have a role in the onset of such lesions. Background. Few cases of cutaneous lymphocytic hyperplasia secondary to vaccintion have been published, although such lesions are not rare. Patients and meth ods. We report a series of 10 cases registered between 1993 and 2003. Results. Age was 25. The clinical aspect was solitary or multiple subcutaneous nodule s, located on the arm, developing after a delay of 1 to 18 months after vaccinat ion. Histologic examination showed a lymphocytic infiltration of the subcutaneou s fat, with diffuse and / or follicular pattern, without nuclear atypia, the morphological and immunohistochemical analysis of which revealed the benigh nature. I n all cases, there was fibrosis and granuloma composed of lymphocytes, plasma ce lls, eosinophils and macrophages with basophilic cytoplasm. Morin stain showed i ntralesional aluminum in the 6 investigated cases. Evolution was always benign, with no relapse following exeresis. Discussion. Cutaneous lymphocytic hyperplasia secondary to vaccination has to be suspected in a young patient with subcutan eous nodules appearing at a vaccination site. Evidence of aluminum in the lesio ns supports the diagnosis and the hypothesis that the aluminum in the vaccine excipient might have a role in the onset of such lesions.