To the fourth declension belongs feminine and masculine nouns which ends with -a in singular nominative. Some nouns ending in -a are masculine or feminine according to the sense in each context (nelga, nepraša, etc.) . The case endings are given in following table:
| Gend. | Nom. | Gen. | Dat. | Acc. | Loc. | Voc. | |
| sing. | fem. | -a | -as | -ai | -u | -ā | -a |
| sing. | masc. | -a | -as | -am | -u | -ā | -a |
| plur. | -as | -u | -ām | -as | -ās | -as |
Diminutives has no ending in singular vocative.
| Nominative | lap-a | lap-as |
| Genitive | lap-as | lap-u |
| Dative | lap-ai | lap-ām |
| Accusative | lap-u | lap-as |
| Locative | lap-ā | lap-ās |
| Vocative | lap-a | lap-as |
| Nominative | puik-a | puik-as |
| Genitive | puik-as | puik-u |
| Dative | puik-am | puik-ām |
| Accusative | puik-u | puik-as |
| Locative | puik-ā | puik-ās |
| Vocative | puik-a | puik-as |