Spatial distribution of InGaN photoluminescence (PL) at room temperature has been examined by observation through an illumination-transmission mode scanning near-field optical microscope (SNOM). The near-field PL mapping revealed a disuniform pattern of sharp or blunt emission peaks from few hundreds of nanometer extension to the micrometer scale range. The peaks' average amplitude size and distances from neighboring peaks have been measured in a large number of experiments for three different samples at dissimilar indium doses, and their results compared. A general trend has been found and the influence of indium concentration is shown in a final plot. We describe the experimental approach adopted and present full details on the results obtained. Data were gathered from more than 100 different measurements; low-cost optical SNOM nanoprobes were originally fabricated and we briefly explain the fabrication procedure. (C) 2004 Elsevier B.V. All rights reserved.