Ergotism is a clinical condition known since old times and whose main characteristics are ischemia and even limb gangrene. Some drugs have the capacity of interacting with small amounts of ergotamine or its derivatives producing ergotism as a side effect. This is the case of ritonavir, a widely used anti-HIV drug. Here we present a case of ergotism that developed in an HIV positive 39 year old male under treatment with ritonavir, after taking 1 mg of ergotamine tartrate. His clinical picture, apart from showing the basic manifestations of the disease, was associated with splenic infarction. For this reason, we consider important to advise patients about the potential pharmacological interaction between ergotamines and others common drugs and, in particular, ritonavir in HIV positive patients.