The paper addresses one of the aspects of poetic imagery in the poetry of Tomas Tranströmer, namely his usage of colours, which has not been discussed as a whole so far. Since Tranströmer’s imagery is mainly based on sensory impressions, especially visual ones, a question arises as to how he transforms sensations into poetic images and how nature is depicted as far as colours are concerned. The analyses show that Tranströmer’s visions capture the very first visual impressions without rationalizing them. Colours are not treated as constant features of things concerned, but as abstract and fresh impressions, as if perceived for the first time. Consequently, colours appear as intense and bright against a nonspecific background or they are difficult to define due to the light which makes them flickering and unstable. Apart from their purely visual qualities, colours often form synesthesiæ with other senses, especially sound impressions.