A simple diffraction experiment was designed using banana stem as natural grating. Coherent beams of lasers with wavelengths of 632.8 nm and 532 nm that pass through banana stem produce periodic diffraction patterns on a screen. The diffraction experiments were able to measure the distances between the slit of the banana stem, i.e. d = (28.76 ± 0.295) × 10[superscript -6] for a laser with a wavelength of 632.8 nm and d = (26.62 ± 0.002) x 10[superscript -6] for a wavelength of 532 nm. Therefore, banana stem could be used as an easily obtained and low cost grating for diffraction experiments.