In 2009, sweet potatoes with foot rot symptom were collected in Changhua and Taichung. Fungi isolated from the symptomatic tissues were diagnosed Phomopsis destruens (Harter) Boerema, the causal agent of sweet potato foot rot disease, based on the morphology and host range. The internal transcribed spacer (ITS) nucleotide sequences of the fungal isolates were highly identical to that of the foot rot disease pathogen SPPD-1 isolate. All plants propagated from the diseased cutting showed symptoms, but the healthy plants could be obtained using sterilized substrate to cultivate the disease-free parts of the infected sweet potatoes. Inoculation of P. destruens on different cultivars of sweet potatoes, showing that all six tested cultivars ”Tainung No.57”, ”Tainung No.66”, ”Tainung No.71”, ”Tainung No.72”, ”Tainung No.73” and ”Taoyuan No.2” were infected. However, the area under disease progress curve (AUDPC) values of the six cultivars were not significantly different. Linear regression analysis using the severity data of foot rot disease showed the relationship of the disease severities over time (weeks) was y = -7.55 + 1.906x.