Abstract. Nominative-partitive alternation in subject marking in Estonian occurs mainly in existentials and related constructions. The paper measures the overall frequency of use of partitive subjects (PS) in Estonian dialects to explore whether differences are found, which can be explained by language contacts. Second, it provides an overview of constructions where PSs occur in Estonian dialects. The data is obtained from the Corpus of Estonian Dialects (12 subdialects, 1517 instances of PS usage). The results show that in usage frequency of PSs, Estonian dialects are relatively uniform and there are no striking differences between the dialects. The use of PSs was less frequent in Northern-Seto (a South-Estonian subdialect, in the Russian contact area), where the use of PSs is more tightly associated with negative clauses than it is in other dialects. Negation is also generally the most powerful factor conditioning the use of PSs (explains 52% of the usages of PSs).