This paper explores the allomorphy of nominal plural suffixes in Iquito, a language of the Peruvian Amazon. There is very little previous research on Iquito plural markers, but the data collected to date do illustrate immense complexity. There are around 20 plural suffixes and in many instances the suffixes do not appear in complementary distribution. The current study presents the first in-depth analysis of Iquito plural markers and reveals that explaining their conditioning environments requires looking at semantic, morphological and phonological factors. It is argued that these competing conditioning factors can partially account for the lack of purely complementary distribution. Furthermore, this study proposes that the complexity within phonologically conditioned suffixes may be due to and, thus, revealing of processes of historical change. Using statistical analyses in conjunction with sound changes observed in other aspects of the language, I hypothesise a preform for the phonologically conditioned plural allomorphs.