Monopole slot antenna is suitable for handset applications due to its simple planar structure. Besides that, it is compact, low cost, low profile and easy to manufacture. It also has wide bandwidth and omnidiractional charatriesticts. The monopole antenna is obtained by cutting monopole slot at the edge of the ground plane of the antenna. These slots operate as the radiating elements of the antenna. The objective of the project is to design a multiband planar monopole slot antenna. This design tool used is the Zeland IE3D software. The proposed antenna consists of two slots cut at the edge of a 100×40 mm ground plan. The antenna occupies an area of 50×40mm. A microstrip feedline is used to feed the antenna. The proposed antenna can operate in GSM 850, GSM900, GSM1800, and GSM1900. It has two wide bands centered at 862MHZ and 1768MHZ. The frequency range of the lower band is from 811MHZ to 981MHZ. The frequency range upper band is from 1572MHZ to 2503MHZ. The antenna has high return loss with 2:1 VSWR. The bandwidth percentage of the lower band is 18.97% whereas the upper band is 45.68% at-10dB return loss. The efficacy of the antenna is greater than 70%.