The seasonally dry tropical forest in Ankarafantsika National Park, northwestern Madagascar, has a prolonged dry season (April-October) and the quartz-rich sandy soil with low water retention. Although drought-deciduous habit of trees is common in forests with prolonged dry seasons, evergreen broadleaf trees dominate this site. This study aims to quantify interspecific and seasonal variations of stomatal conductance (g_s, the degree of stomatal pore openness), which is known to play a central role in drought adaptation via its influence on photosynthetic carbon gain and the risk of leaf dehydration. Along a 8-m-wide trail, we selected 20 broadleaf tree species (10 evergreen species, 5 late-deciduous species retaining leaves until the late dry season, and 5 early-deciduous species leafless throughout the dry season). Using a porometer combined with fluorometry (LI-600 PF), we repeatedly measured g_s and electron transport rates of sunlit leaves from 3-4 individuals per species during the rainy (late February-early March) and the dry (early September) seasons. We also measured several leaf traits, including stomatal size and number and leaf cross-sectional anatomy. During the rainy season, g_s ranged from 0.14 to 0.55 mol m^-2 s^-1 and decreased in the order of early-deciduous > late-deciduous > evergreen species. Across species, g_s was positively correlated with maximum electron transport rate (J_max), and negatively correlated with leaf mass per area (LMA) and leaf thickness, indicating the coordination of the stomatal conductance with leaf economics spectrum (LES). Stomatal pore index (SPI = stomatal density × stomatal length²), was also positively correlated with g_s. During the dry season, g_s remained below 0.1 mol m^-2 s^-1 throughout the day in most species. Nevertheless, the dry-season g_s was positively correlated with the rainy-season g_s in evergreen and late-deciduous species. A principal component analysis shows that stomatal length varied positively with mesophyll cell size and leaf lamina area, but negatively with stomatal density and leaf tissue density. Moreover, these cell-size related variables were orthogonal to g_s and other LES-related traits. The high variability in these traits along with differences in the dry-season g_s, suggests functional diversity in combining drought avoidance and drought tolerance strategies in this seasonal dry forest with the prolonged seasonal drought.