The mail survey is a popular data collection tool in developed countries, but little is known about its use and efficacy in developing countries. Grounded on social exchange and diffusion of innovations theories, this study sought to ascertain whether the mail survey works in Nepal -- one of the developing countries, by looking at how long respondents take to respond to mail surveys, and what the determinants are of the response time. A mail survey was conducted in June-September 2012 among 863 village animal health workers. Analysis of the data derived from 500 usable surveys shows that if properly planned and executed, the mail survey will perfectly work in developing countries as well. However, response period greatly varied by respondent's home region, program sponsor, income groups, but not by gender, age, and education. The paper concludes by outlining suggestions to improve the mail survey.