Tomato is one of the most economically important vegetables in the Dominican Republic. The global distribution of relevant diseases such as fusarium wilt produced by Fusarium oxysporum f. sp. lycopersici (FOL) is a limiting factor in production and a major cause of losses in the horticultural areas of the country. Fusarium wilt is a disease difficult to diagnose because of pathogenic variability of the fungus. The accurate diagnosis is the basis to efficiently control the pathogen. The objective of this research was to determine Fusarium oxysporum race present in the tomato crop by PCR. Analyses were performed at the Laboratory of Plant Pathology-IDIAF at CENTA. We proceeded to isolate the fungus from diseased tissue of tomato plants with wilt and collar rot, collected in the province of Azua, which is the major tomato producer in the country. There were 12 isolates identified taxonomically as F. oxysporum. To determine the race of the fungus, molecular analysis was performed by PCR, in which the strains were evaluated using specific primers of FOL, following the protocol proposed by Cai et al. (2003). The results obtained by comparing the DNA bands amplified from samples of diseased plants, reveal that three of the isolates belong to F. oxysporum f. sp. lycopersici race 3 (Jarvis y Shoemaker, 2004), phytopathogen unreported in our country, thus this work is the first report of this pathogen for the Dominican Republic.