Image processing techniques have been widely used as a non-destructive method to determine the maturity of agriculture products. In the past few decades, numerous fruit maturity grading systems have been proposed and developed. However, there is no system or technique is reported to determine the maturity for Sarawak’s brinjal. Therefore, in this research, a colour image processing-based method is proposed in order to determine the maturity of Sarawak’s brinjal based on the skin colour. Ripe Sarawak’s brinjal has yellow or orange colour skin while unripe Sarawak’s brinjal has green colour skin. The proposed method consists of four main phases which are image acquisition, image pre-processing, features extraction, and classification. CIELAB colour model is used in this proposed method. The RGB value extracted from the image is converted into CIELAB colour space in order to obtain the CIELAB value. The maturity of the Sarawak’s brinjal is determined based on the colour difference between the fruit and the reference colour. In the experiment, a total of 48 Sarawak’s brinjal sample with 24 sample for each grade (ripe and unripe) were prepared. 12 out of 24 samples from each grade were used for thresholding. From the experimental results, a total of 23 Sarawak’s brinjals were correctly classified out of 24 Sarawak’s brinjal sample, accounts for nearly 96% of accuracy.