This paper classifies Slavic languages according to their accusative plural patterns. Modern Slavic languages with six or seven-case declension systems share the same singular nominal accusative case pattern based on the grammatical category of gender and the semantic category of animacy. On the other hand, these Slavic languages have different accusative plural patterns which can be classified into four groups with their own binary privative oppositions. The first Slavic accusative plural group consists of Slovene and BCS whose accusative plurals marked with [+Masculine] have their own accusative forms, while unmarked ones are replaced with their nominatives. Russian, Ukrainian, and Belarusian belong to the second Slavic accusative plural group where only the semantic feature [+Animate] plays a role, assigning the marked genitive-accusative form to animate accusative plural nominals and the unmarked nominative-accusative form to inanimate ones. The third group includes Czech where only the plural nominals with [+Masculine, +Animate] obtain their own accusative plural forms, while the unmarked rest have nominative-accusative forms. Polish and Slovak belong to the fourth group with the strictest criteria according to which only the accusative plurals with [+Masculine, +Animate, +Human] are marked with genitive-accusative and the other unmarked accusative plurals share their nominative forms.