Out of patients with petechial lesions attended during a 5 year period, 90 (45%) were diagnosed a meningococcal disease. The generalized distribution of the petechial lesions proved to be very helpful as an orientation about the disease. The presence of a series of altered laboratory determinations (white blood cell count, band cells count, erythrocyte sedimentation rate 1st hour. C reactive protein (PCR) in blood and blood coagulation study) was highly significant in patients with the disease mentioned before.