The use of wireless local area networks (WLANs) is experiencing a significant growth. Infrared technology has an extensive bandwidth of free use, and has the potential to be the support of high-baud rate WLANs. For that, it is necessary to understand the propagation characteristics of the indoor optical channel. This paper presents a computationally effcient algorithm for the simulation of indoor optical channels, considering multiple reflections of the emitted signal. The models used to approximate the emitter pattern, the propagation environment and the receiver pattern are described. Two new procedures (called Time Delay Agglutination and Time and Space Indexed Tables) are introduced to increase the effciency of the simulation of the impulse response of the indoor wireless optical channel. The structure of the algorithm is presented and the approaches used are discussed. The new algorithm was implemented in a simulation package, named SCOPE, which is very effcient and allows to evaluate the main parameters of indoor optical channels considering multiple reflections of the emitted signal. Results obtained for several channels are compared with experimental and published values, and good agreement is verified.