BACKGROUND: In 1998/99, the British Columbia Medical Association (BCMA) asked physicians to withdraw elective services on a series of 20 Rationed Access Days (RADs). This work stoppage was called to protest continued free proration triggered by total physician billings exceeding a fixed budget cap. This paper examines how physicians' practice activity changed on RADs, the rates of participation in this job action and characteristics of those physicians who participated. DESIGN: Population-based cohort study of physicians based on administrative data. POPULATION: All full-time physicians billing the provincial healthcare plan. METHODS: Participation in the RAD initiative was inferred by comparing physicians' average daily billings on RADs, Sundays, holidays and regular weekdays. Using thresholds established from these distributions, the number of RADs observed by each physician in 1998/99 was calculated and examined in relation to their demographics, location and prior years of practice activity. RESULTS: For the 4,131 physicians studied, average daily payments on RADs were similar to those on Sundays and holidays but much lower than those on non-holiday, non-RAD weekdays. Using billing thresholds of $200 (for GPs) and $400 (for specialists), we found a high degree of participation with the study population observing a median of 15 of the 20 scheduled RADs. While there were some differences in participation among age groups, geography and the prior years of practice activity, the differences were small. INTERPRETATION: This study found high solidarity in the BCMA's 1998/99 RAD initiative. Most full-time fee-for-service FS physicians appeared to participate in at least three-quarters of the 20 scheduled RADs.