A study is presented on the spectroscopic properties of a sample of star- forming dwarf galaxies in extreme density environments, as part of an ongoing project intended to evaluate the influence of the environment on the evolution of dwarf galaxies. Subsets of dwarf galaxies in nearby voids, and in the field of the local supercluster have been selected to characterize lower density regions. Conversely, higher density environments have been characterized choosing a subset of galaxies in the direction of the core of the Virgo Cluster, as well as an isolated clump of galaxies. Our findings indicate that, overall, the spectra of those star-forming dwarf galaxies located in low-density regions tend to present higher excitations and ionization parameters, higher Hβ equivalent widths, and larger total Hβ luminosities than similar objects located in higher density environments. At the same time, only marginal evidence may be found supporting a trend between the gas metallicity and the density of the environment. The general metallicity luminosity relation for dwarf galaxies appears to be followed by most galaxies in the sample. An analysis of the spectroscopic ratios of the galaxies using recent evolutionary models of giant H II regions suggests a mixed star-formation history for most of the Virgo star- forming dwarfs, requiring continuous star formation in addition to some currently observable bursts.