The study of health tourism based on the consumption of traditional herbal sexual stimulants and fertility enhancers is an exceptional ordeal. Research in this field has proved methodologically demanding as the population constitute the hard-to-reach group (hidden populations). Consumers of these traditional herbal prescriptions generally are floating populations and socially invisible thus getting hold of them poses major challenges. This paper focuses on highlighting the issues underlying the study of hidden populations, with a particular focus on traditional herbalists and the consumers of indigenous sexual stimulants and fertility enhancers. Certain specific methodological challenges are faced by researchers working with hidden populations, and this paper explores these in the field of health tourism based on the consumption of indigenous herbal medicine. Particular focus is paid to the methodological challenges involved. The paper's main contribution is to highlight and emphasize the methodological problems that emerge when studying socially invisible populations and to showcase the inadequacy of some existing methods to recruit these hidden populations.