With the growing importance of the international service trade right round the globe, Sri Lanka, a country with more than 50% of its GDP being contributed by the service sector, cannot overlook the trade gains that it can reap by getting deeply involved in International Trade in Services. If Sri Lanka wishes to participate enthusiastically in International Trade in Services and trade in services agreements it is of utmost importance for Sri Lankan policy makers to identify commercial service sector industries that have comparative advantages at both regional and global level. The study employs five Revealed Comparative Advantage indices to measure the comparative advantage and to measure the stability of the specialization pattern, uses Revealed Symmetric Comparative Advantage Index. In order to establish the consistency of the indices the study uses cardinal, ordinal and dichotomous tests. The study identifies Travel, Communication and Insurance industries as comparatively advantageous to Sri Lanka at both regional and global levels and Transportation and Construction services industries as having comparative advantage at regional level.