I second Hospital Rivadavia. I'd become ill in winter in BA in 2007 and had called every private doctor or clinic near my Recoleta apartment. No one would book me an appointment: they were either on holiday or the first available appointment was days away. Therefore, I went to Hospital Rivadavia which was the closest hospital to me. Upon entering it, I became worried because it was so decrepit and scary that I thought I was watching a Tarkowski film. Since I had nowhere else to go, I sat on the floor in a waiting room after I registered myself at reception. To my complete surprise, I was seen within 15 minutes (!) by a great doctor who spoke English and kept fantastic care of me, and treated me for a light case of pneumonia. He didn't hurry his treatment and gave me better and faster emergency care than I receive in the emergency departments of hospitals in Canada. The doctor was very knowledgeable, even knowing the North American brand names of drugs which are different from Argentina's. If I ever get sick again in Argentina, I will go to this hospital again without looking for a private practitioner. I think I brought my passport with me, that's all.