The arbitrary relation between sound and meaning is a fundamental assumption of modern linguistic theory. However, psycholinguistic literature also reports evidence for iconicity of phonological symbols. Here, we focus on phonological iconicity or sound-meaning mappings with regard to affective word content. Analyses of affective ratings for a large-scale database of German words suggest potential sublexical affective values for certain graphemes, as they occur more frequently in words of certain affective meaning. Using a letter-search task, we investigate how these systematic mappings between phonology and affective word content influence online language processing. Responses were generally shorter for high-arousal target graphemes-involving crucial interactions with affective word content. Iconic form-meaning mappings regarding affective content seem to influence both the organization of the vocabulary and the processing of language using phonological units of high perceptual salience to iconically encode threat or alert. (PsycINFO Database Record (c) 2018 APA, all rights reserved).