Fowl cholera (FC) was studied during a ten-year period (January1986through December 1995) in Taiwan. Total of 680 cases (including 381 duck cases and 255 chicken cases) were analyzed in a time series study. Peak seasonality for all cases was from July to August and in December, while duck cases peaked in August and November to December and chicken cases peaked in March and July. The cycle curve revealed two major epidemics in ducks (Sept. 1989 and May 1990) and one major epidemic in chicken (July 1989), with no apparent periodicity. By regression analysis, FC occurrence showed a slowly declined trend over ten-year period, especially in chickens (P=0.0002).