Different applications of wireless sensor networks (WSNs) have different expectations from the working of medium access control protocols. Some value reliability more than delay incurred while some demand a fair trade-off for the factors like: Throughput, bit error rate etc. This paper evaluates the performance of wireless personal area networks from 802.15.4 group for WSNs with modified algorithm which helps in reducing the medium access delay and delay in reaching of the packet from one end to another end. In this paper certain modifications to existing algorithm have been proposed for reducing the medium access delay and to reduce the number of packets dropped. The result comparisons on the performance parameters like: network output load, generated acknowledged traffic, media access delay, battery consumed and delay in packet transmission from one end to another end that the backoff number and exponent values used for transmission play vital role for improving the performance of WSNs as they directly affect the number of packets dropped, successfully acknowledged and medium access delay.