Changes in the composition and structure of mid-altitude, semi-deciduous tropical forest in Mpanga Research Forest Reserve, Uganda are described for a 25-year period between 1968 and 1993. Three surveys of a 0.64 ha (80 m × 80 m) permanent plot were carried out in 1968, 1982 and 1993, during which a total of 397 trees with a dbh≥9.5 cm were identified. Forty-nine species were identified in total, representing 19 families. Eight individuals remain unidentified. Dbh measurements were recorded for 359 non-buttressed trees, whilst the equivalent measurement for 38 buttressed trees was the diameter of the trunk immediately above the buttress. Basal area, diversity and density of trees increased within the plot during the survey period by, respectively, 8% (from 39.2 to 42.2 m2 ha−1). 7% (from 44 to 47 species) and 11% (459 to 508 trees ha−1). The main compositional changes were increases in understorey trees and a decline in serai taxa. Growth rates (productivity) and turnover were lower during the period 1982 to 1993 than the period 1968 to 1982. Rates of growth and mortality were generally highest in serai species and lowest in main canopy taxa. Mortality rates were also highest amongst the smallest trees enumerated (dbh <30 cm). Changes in composition and structure over the survey period are believed to reflect forest recovery after low intensity pit-sawing was curtailed from 1951. Forest recovery also may have caused the reduced growth rates and turnover recorded for the most recent survey period, by restricting the opportunities for light-demanding, faster-growing and relatively productive serai taxa, and to have outweighed any effects of externally-driven processes, such as changes in atmospheric conditions.