Wetlands are one of the most threatened natural ecosystems on the planet. In spite of their recognized importance, wetlands are not highly valued. This is particularly true in Chile, where little information is available regarding this type of environment. This paper presents data on the typology, hydrology, land uses, landscape units, and impact of 20 wetlands in regions IV (Coquimbo) and V (Valparaiso) of central Chile. Samples were taken from 2 to 10 July 2007, during the wet phase of the annual hydrological cycle. We analyzed a variety of physical-chemical (depth, width of the water surface, substrate typology, temperature, pH, water conductivity) and biological parameters (aquatic and shoreline vegetation, macroinvertebrates, ichthyic fauna). We used the Index of the State of Conservation of Shallow Lentic Ecosystems (ECELS), proposed by the Catalan Water Agency, to determine the state of conservation of these wetlands. In general, this index deals with mid-sized ecosystems that do not exceed 50 ha although, herein, the Yali complex (Region V) is an exception (>500 ha). Most of these systems are permanent and average 7,84 in pH (range = 7,1-9,4) and 11918,2 [mu S/cm in conductivity (range = 665-52200 mu S/cm). The very wide range showed different origins of the waters that sustain these wetlands. As for the aquatic vegetation, Ceratophyllum chilensis is the most common macrophyte in low-conductivity wetlands. The aquatic invertebrate community is composed of 42 taxa belonging to 29 families. Insects constitute the most diverse group (17 families), particularly the dipterans (8 families). Four fish species were collected during sampling. One, flathead mullet or lisa (Mugil cephalus), has marine origins and the other three are exotic species: mosquitofish or gambusia (Gambusia holbrooki), tell spotted live-bearer (Cnesterodon decemmaculatus), and chameleon cichlid (Cichlasoma facetum). According to the ECELS. the quality of these wetlands is maximum in only two cases, good in five, regular in seven, poor in another five cases, and very poor in one case.