This paper proposes several microstrip multi-band patch antennas for mobile device applications. With simple designs - Rectangular Microstrip Antennas (RMSA) with slots on ground plane and radiating elements printed on the no-ground region, these antennas have small dimensions (35x48x1 mm3) and operate at multiple frequency bands, such as GPS(1564 - 1583MHz), DCS(1710-1880MHz), PCS(1850-1990MHz), UMTS(1920- 2170MHz), WiMAX(2500-2690/34003600MHz), WLAN(2400-2484MHz/5150-5350MHz/5470-5725MHz/5725-5875MHz). The antennas are printed on a Roger substrate with thickness of 1mm and dielectric constant of 2.3. The design process was carried out by using CST Microwave Studio and the prototypes were measured and tested by ZVB8 Vector Network Analyzer.