Size at reproduction is a key aspect of species life history that has been little explored for long-lived tropical trees. In this study, we aimed to quantify reproductive diameter for 31 major timber species across 11 sites in Cameroon, Congo, and Central African Republic. Specifically, we examined (1) whether between-species variability can be explained by a set of seven species traits; (2) whether reproductive diameter varied within-species among sites; (3) whether reproductive status varied with crown exposure; and (4) whether the minimum cutting diameter limits (MCDL) imposed by national forest regulations enable the persistence of seed trees after logging operations. In accordance with studies conducted elsewhere in the tropics, we found a great variability in diameter at reproduction among species that was correlated with adult stature (maximum diameter and height). For some species, reproductive diameter thresholds showed substantial variation between sites, and crown exposure had a significant positive effect on reproductive status. The majority of MCDLs was found to be suitable, trees having high probability for being seed trees at MCDL. As the most complete assessment of size at reproduction for timber species in central Africa, the study has implications for the sustainable management of production forests, highlighting questionable MCDL for some species and between-site variation in reproductive diameter. The study also highlighted the need for long-term phenological monitoring of tree species spanning a large range of ecological strategies to address both theoretical (species life-history, allocation trade-offs) and practical questions (MCDL).