The growth and demography ofCubitermes speciosus mounds were studied in an equatorial forest ecosystem near Kisangani, Zaire. The mounds were censused and measured on eight occasions from June 1985 to January 1993 on 25 plots of 100 m2. Mounds were found to grow in two ways: either they were enlarged sporadically, leading to a correlation between age and size; or they were no longer enlarged after a 2-year period of initial growth, which means that both large and small mounds can be old. The number of living mounds was fairly constant: it varied between 112 and 152 ha−1 with an average of 139 ha−1, and about a quarter of them were renewed each year. However, a clear tendency was observed over our 7.5-year observation period: the average size of the mounds increased regularly and was 2.7 times larger in 1993 than in 1985. Monthly birth and death rates were estimated using a model of continuous growth. Life expectancy at the age of 3 months was estimated from a survivorship curve at 3.5 years.