The need for high speed networks has motivated the telecommunication community to investigate the potential of Optical Code Division Multiple Access (OCDMA) in local area networks. However, Multiple Access Interference (MAI), which increases with the number of simultaneous users, severely limits the capacity of the system. Optical Parallel Interference Cancellation (OPIC) has been used to reduce the effect of MAI. The drawback of OPIC is that, it increases the demand for hardware complexity, resulting into higher processing time and cost. To overcome these difficulties, an efficient method is presented in this paper called, One Stage Optical Parallel Interference Cancellation (OS-OPIC) which is based mainly on OPIC. Performance analysis of the proposed design is done using optical Orthogonal Code (OOC) as signature sequence and new expression for error probability is demonstrated. It is shown that, the proposed method is effective to reduce the hardware complexity, processing time and cost while maintaining the same bit error probability at the cost of increasing threshold value. © 2007 IEEE.