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The biological soil activity is responsible for several physical and chemical transformations of deposited organic residues, therefore maintaining the environmental sustainability. The aim of this study was to evaluate the distribution of the soil microbial community and mesofauna in a dry forest (Caatinga) in the semi-arid region of Paraiba, northeastern Brazil. To determine the microorganism population soil samples from the 015 cm soil layer were evaluated. Total counts of fungi and bacteria were evaluated in specific culture media. The Berleusse-Tulgren modified method was used to extract the soil mesofauna. Oscillations in the soil water content and high temperatures promoted variations in the microbial population. The fungi population was larger than that of bacteria in both years of the study period, probably due to the slightly acidic soil pH. Shannon’s index (H) and Pielou’s index (e) also varied according to the season of the year. The most important mesofauna groups are Diptera (42.5 %), Acarinae (40.3 %) and Collembola (8.8 %). These groups play an important role in nutrient cycling in dry forest sites.