This paper investigates calendar anomalies in the Turkish foreign exchange markets during 1986-1994 period. Changes in the free market and official daily exchange rates between the Turkish lira (TL) and US dollar (USD) and the German mark (DM) are examined for empirical regularities on different days of the week, around the turn of the month and before holidays. The findings reveal that free market rates exhibit day-of-the-week and week-of-month effects. In addition free market DM returns display a holiday anomaly. These calendar anomalies are explained by cash disbursement patterns, together with currency substitution in the economy. The impact of treasury auctions and banks' management of liquidity on day-of- the-week effect is also discussed.