1. In the coastal area of Suriname the soil and surface fauna were studied in various types of agricultural land, and compared with the fauna in the adjacent forests. 2. In primeval forest the soil macroarthropods are less numerous than in secondary forest (Formicidae excluded). They range generally from 2,000 to 3,000 per m2 in the primeval forest and from 3,000 to 4,500 per m2 in the secondary forest. In cultivated land the numbers range in general from 1,500 to 2,500 per m2. In recently reclaimed land the numbers of soil macroarthropods are very small and amount to 15-30% of those in the adjacent forests. In the older agricultural soils they range from 50 up to 130% of the numbers of arthropods in forest soil. 3. The surface fauna is best developed in the secondary forest on shell ridges. In primeval forest the surface fauna is richer in the border zone than in the inner part. In cultivated land most “forest species” decrease strongly in numbers, but they are replaced by “open field species”. The numbers of surface arthropods (Formicidae, Scolytidae and Pheropsophus excluded) in the cultivated land are generally 20-40% less than in the adjacent forests. 4. On account of their much more frequent occurrence in forests the following groups were distinguished as forest inhabitants: Isopoda, Diplopoda, Dermaptera, and Staphylinidae. The following may be designated as open-field inhabitants: Lycosidae, Gryllotalpidae, Elateridae and Pheropsophus (Carabidae). 5. Of the eleven most frequent indigenous diplopod species, five were exclusively found in forest land; another five were also taken in cultivated land, but in much smaller numbers; and one species only was more numerous in the fields than in the forests. – Three introduced species were found in greater numbers or exclusively in cultivated land. One of these was only taken near Paramaribo, probably the centre of introduction. 6. In the cultivated land the number of ants active on the surface of the soil exceeds that in the adjacent forests by up to 900%. The ant population in the soil of cultivated land is generally only 10- 30% of that in forest soils. 7. Three of the 171 species accounted for about one third of all the ants collected. These occurred in nearly all fields and forest plots, and apparently have the widest ecological range. The qualitative composition of the ant fauna in the forests appeared to be much richer than that in the fields. 8. The microarthropod population (Acari and Collembola) in the cultivated land was surprisingly large and averaged 80% of that in the forest land. 9. There were no indications that the soil fauna (macroarthropods as well as microarthropods) is consistently smaller in the Surinam soils than in the Dutch soils. However, the greater production of plant material in the tropics and the absence of litter accumulation point to a more rapid decomposition, caused by a greater biological activity at the higher tropical temperatures.