Contemporary techno-scientific and medical developments are restructuring social interactions and the very processes by which individual subjectivity is formed. This essay elaborates on the experiential and ethical impact of such transformations from the perspective of people who, in ordinary and unexpected ways, act science and technology out. We carried out ethnographic research in an HIV/AIDS Testing and Counseling Center (CTA) in northeastern Brazil, combining participant observation with epidemiological analyses and clinical survey. We found a high demand for free testing by low-risk clients, largely working and middle class, experiencing anxiety and complaining of AIDS-like symptoms. Most of the clients were sero-negative and many returned for a second and third testing. We understand this to be a new techno-cultural phenomenon and call it imaginary AIDS. Throughout this essay, we describe CTA's routine practices, place these practices in historical, political, economic and cross-cultural perspective, and analyze the subjective data we collected from the clients of our pilot study. We explore how clinical epidemiological expertise and HIV testing technology are integrated into new forms of bio-politics aimed at specific marketable and disease-free populations, and on the affective absorption of bio-technical truth and the engendering of a technoneurosis in this testing center.