This is a report of three cases of mycetome studied in our laboratory during the last four years. We also informed about the evolution of the first case produced by Pyrenochaeta romeroi nova species reported by Borelli in 1959. All the patients were farmer men, 18, 42 and 54 years old, from the semiarid and subhumid zones of Falcon State, located on the northwest region of Venezuela. Clinically, all patients presented the mycetome syndrome (subcutaneous edema, sinus tract and "granules"), with a evolution of six months to three years. The lesions were localized in the inferior limbs in two of the patients and in the thorax in one of them. The clinical diagnose was confirmed by microbiological and mycological studies, isolating Nocardia brasiliensis in two cases and Madurella grisea in one. Two patients treated with Sulfas showed remission of the disease in a two years follow up. Including this report, 15 cases of mycetome have been reported in the Falcon State (Venezuela) in a period of thirty five years, representing only 9, 14% of the national casuistic. Actinomadura madurae and N. brasiliensis have been the most frequently isolated agents in this region. In order to determine the real endemicity of the mycetome in Venezuela, multidisciplinary clinical, inmunological, microbiological and epidemiological studies are recommended. According to the reported casuistic (15 cases), the mycetome should be a low frequency disease in Falcon State, Venezuela. We confirm that early diagnosis favors an efficient therapy.