A study was made of the temporal fluctuation in the population density of Meloidogynefujianensis parasitizing the roots of Citrus reticulata growing in Nanjing County, China. The lowest infection rate occurred in August (30%), and the highest in April of the following year (90%). The lowest average infectivity was re-corded in August (1.8 females/2g roots) and the highest in February of the following year (24.2 females/plant). Infection occurred throughout the year with peaks of infection in September and October and again in March to April of the following year. The peak of oviposition occurred during December and January. The population density increased with increasing monthly average temperatures. The most active growth of C. reticulata roots coincided with the peaks of infection of nematode juveniles (September-October, March-April), which was as-sociated with two main periods of disease symptomatology. The ratio of males decreased with increasing monthly rainfall.