To evaluate the effects of four kinds of organic non-living mulches (wheat straw, sawdust, coco peat and peat moss) and metribuzin (herbicide treatment) on weed control and yield of tomato cv. "CH" an experiment was designed in randomized complete blocks with 7 treatments and 3 replications at the College of Agriculture, Shiraz University in 2012. According to the results all mulch treatments showed lower efficiency in weed control than the metribuzin. Also, all mulch treatments showed higher weed density compared to metribuzin. When straw, among non-living organic mulches, showed lowest weed control (62.3 weed.m-2). According to the results the highest tomato yield per unit area was produced by using peat moss mulch (from 5.7 kg.m-2) and the lowest yield from weedy plots (1.2 kg/m-2). To calculate the percentage of predicted performance of each of the treatments, only Gompertz model was applied and only the beginning of weed interference between the treatments was taken into account