A rigorous comparative study on local area network technologies: Ethernet, ATM and WLAN with respect to the delay and throughput in each system are done in this paper. These three technologies are prominent and used on a commercial scale in homes, campuses, offices, industries, etc. However, the data communication requirement and the working condition are not same in these places. The cost of these three technologies also is not the same. The paper compares the three technologies and can be helpful in selecting the LAN (Local Area Network) technology according to the requirements and place of deployment.