The objective of the present study is to examine the error patterns for Persian reading and spelling when controlling for the complexity level of words. A sample of 140 children attending Grades 1-4 in Iran read and spelled the same words that differed in reading transparency (transparent vs. opaque) and spelling consistency (monographic vs. polygraphic). Children's reading and spelling errors were analyzed for four types of words including transparent-monographic, transparent-polygraphic, opaque-monographic, and opaque-polygraphic. Children, across all grades, read transparent-monographic words as accurately as they spelled the same words, however, the opaque-polygraphic words, the hardest categories of words, were read more accurately than they were spelled. Moreover, children read transparent-polygraphic words more accurately than they spelled these words. The opposite pattern was observed for opaque-monographic words, that is, these words were spelled more accurately than they were read. Further examination of errors revealed that the words that children most often read correctly but spelled incorrectly were polygraphic, and the words that children most often spelled correctly but read incorrectly were opaque. Further, fine-grained analyses of reading and spelling errors revealed that the degree of the complexity level of words also increased error rates for both polygraphic and opaque words. These results suggest that differences in word characteristics and the complexity level of the words explain the discrepancy in difficulty level between reading and spelling.