Cigarette smoking is the leading cause of lung and bronchus cancer (1). During 1988-1997, per capita cigarette smoking in California declined more than twice as rapidly compared with the rest of the country (2). To characterize lung cancer incidence in California, data from the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program were compared with data from the population-based California Cancer Registry (CCR). This report summarizes the results of that analysis, which indicated that during 1988-1997, age-adjusted lung cancer incidence rates in California declined significantly compared with stable incidence rates for the combined SEER area of five states and three metropolitan areas.