A model for the surveillance of acute, work related pesticide illnesses was described. The method was an application of the Sentinel Event Notification System for Occupational Risks (SENSOR) and was developed by the California Department of Health Services (CDHS) to enhance case reporting of work related pesticide poisonings and to link the case reports to preventive interventions. The method was implemented in 1988 in Fresno County, California which had an agricultural workforce of more than 60,000. The program consisted of 102 county physicians and their clerical staff experienced with treating pesticide related illnesses who were requested to notify CDHS of any new cases of suspected pesticide poisoning they treated. Each case was classified based on criteria which considered factors such as signs, symptoms, laboratory findings, involvement of case patients and witnesses in the exposure incident, and temporal sequence of exposure and illness. Selected worksites where confirmed cases originated were visited to identify factors that led to the exposure incident and to make recommendations for preventing future incidents. There were 230 suspected pesticide poisoning cases reported from October 1988 through December 1991. Of these, 217 from 80 worksites met reporting criteria. A total of 118 case patients were selected for followup, 89 of which were successful. Thirty six employers of case patients were interviewed and 15 worksites were visited. Most case patients were found to have poor educational backgrounds and few had received any training in pesticide use or hazards. The field surveys found that most exposures were to organophosphates and carbamates. Inadequate safety training, nonexistent or inadequate medical monitoring, inadequate personal protective equipment, and lax supervision were also common findings. Of the 117 specific recommendations made to the employers, only seven were identified in reports of the regular agricultural enforcement agencies. The authors conclude that the SENSOR based program has identified risk factors for pesticide poisonings that the regular state agricultural inspectors have not found.