A field experiment was conducted to analyse the competitive ability of three red rice types: Varietal Cica-6 (VC·S), Mechudo Patechulo (MP) y Pipon Desgranador (PO) grown in monoculture and mixture (50:50) wth Oryzica-1. A randomized block design with sampling and three replications was used. Plant heigh, tiller number and leaves per plant, leaf area, plant dry weight and yield components were measured. Leaf area index, net assimilation rate, leaf area ratio, relative growth rate, crop growth rate and leaf area duration were derived. It was found an increase in plant dry weight and RGR in VC-6, plant dry weight in MP and plant dry weight, leaf area and LAR in DP when they were grown in mixture with Oryzica-1 which showed that these parameters are important competitive characteristics of the red rice types. On the other hand, most of the physiological cheracteristics studied in Oryzica.1 decreased when it was grown in mixture with the three red rice types. These results classify Ve6; MP and PO as high, medium and low agressive weeds respectively.