The Réunion Surveillance Network for Influenza, Dengue, and Acute Diarrhea, composed of private practitioners and coordinated by the Regional Health Observatory (ORS), was mobilized to monitor chikungunya as soon as the first cases appeared in April 2005. The objective is to describe the characteristics of clinical cases of chikungunya reported by physicians in the Surveillance Network during the epidemic. This Network initially consisted of 28 physicians, later expanding to 43, spread across 23 of the island’s 24 municipalities. Data on the cases were entered by the Réunion-Mayotte Interregional Epidemiology Unit (Cire RM). Physicians in the Network reported a total of 6,434 cases of chikungunya seen in clinical practice. Patients who consulted Network physicians were more frequently adults and women than in the general population. The most frequently reported clinical signs were fever and joint pain (inclusion criteria), followed by headaches, muscle pain, skin rashes, and then gastrointestinal and other skin symptoms. Clinical differences depending on the epidemic period were observed. The cases reported by sentinel physicians made it possible to estimate the number of new cases occurring in Réunion each week. This surveillance system demonstrated its responsiveness and representativeness during this epidemic, thereby gaining valuable experience in monitoring an emerging phenomenon. (R.A.)