Background: According to the international literature thrombocytopenia is frequent in murine typhus. Methods: One hundred and sixty-one patients with compatible clinical status of murine typhus and high serological titers of antibodies against Rickettsia typhi, were studied from our team, during a period of time between January 1993 and December 2007. Three blood samples were obtained from each patient for the study of their thrombocytopenia. The first sample was obtained on admission, approximately 9 days after the onset of the disease. The second sample approximately two weeks after the first. The third sample, taken from the one third of the patients, was obtained one month after the second. On admission (first sample) 88/161 patients (54.6%) presented thrombocytopenia and the median value of platelets was 141x103 /ml respectively. Two weeks later (second sample) 23/147 patients (15.3%) presented thrombocytopenia. The median value of platelets was 247x103 /ml respectively. One month later (third sample) 2/42 patients (4.8%) presented thrombocytopenia and the median value of platelets was 224.5x103 /ml respectively. Results: Our study showed that thrombocytopenia is frequent in murine typhus on admission of the patients to the hospitals. The number of platelets, according to our results, returns to normal value after almost a month of the onset of the infection. Conclusion: Thrombocytopenia returns to normal values after a month of the onset of the infection.