Background: The influence of religion on demographic behaviors has been extensively studied mainly for Abrahamic religions. Although Buddhism is the world's fourth largest religion and is dominant in several Asian nations experiencing very low fertility, the impact of Buddhism on childbearing has received comparatively little research attention. Objective: This paper draws upon a variety of data sources in different countries in Asia in order to test our hypothesis that Buddhism is related to low fertility. Methods: Religious differentials in terms of period fertility in three nations (India, Cambodia and Nepal) and cohort fertility in three case studies (Mongolia, Thailand and Japan) are analyzed. The analyses are divided into two parts: descriptive and multivariate analyses. Results: Our results suggest that Buddhist affiliation tends to be negatively or not associated with childbearing outcomes, controlling for education, region of residence, age and marital status. Although the results vary between the highly diverse contextual and institutional settings investigated, we find evidence that Buddhist affiliation or devotion is not related to elevated fertility across these very different cultural settings. Conclusions: Across the highly diverse cultural and developmental contexts under which the different strains of Buddhism dominate, the effect of Buddhism is consistently negatively or insignificantly related to fertility. These findings stand in contrast to studies of Abrahamic religions that tend to identify a positive link between religiosity and fertility.