The Efficient Market hypothesis is a cornerstone of modern investment theory that essentially advocates the futility of information in generation of abnormal returns in capital markets over a period of time. However, the existence of anomalies challenge the notion of efficiency in stock markets. Calendar effects, in particular, violate the weak form of efficiency, highlighting the role of past patterns and seasonality in estimating future prices. The present research aims to study the efficiency in Indian stock markets. Using daily and monthly returns of NIFTY 50 data from its inception in January 1995 to December 2015, we employ dummy variable multiple linear regression technique to assess the existence of calendar effects in India stock markets. To correct for volatility clustering and ARCH effect present in the daily returns, the results are modelled using the EGARCH estimation methodology. The study reveals the existence of calendar effects in India in form of a significant Wednesday Effect as well as a significant 'December effect', thereby suggesting that the Indian stock markets do not show informational efficiency even in the weak form, a trait observable in emerging markets.