The present study examines the influence of ambiguity tolerance on the performance of Iranian GFL-learners (Note 1) at level B1 in the processing of gap-filling-text tests. It is assumed that learners with more tolerance of ambiguity achieve better results in the reading comprehension or in the contextual guessing of the omitted words. 34 GFL learners at Level B1 in Iran Language Institute in Mashhad have completed a three-part pilot gap-filling test as well as the pilot questionnaire called SLTAS (Note 2) to assess their ambiguity tolerance. In order to examine the hypothesis and to answer the research question, the total score of the subjects who participated in the pilot and the main study were analyzed by SPSS program version 18.0. The quantitative-correlative analysis did not demonstrate a statistically significant relationship between the tolerance of ambiguity and reading comprehension. In conclusion, with regard to the multi-dimensionality of reading comprehension, and despite the divergent empirical evidence in research literature, it is still advisable to take into account the affective, cognitive, and extra-linguistic determinants of reading comprehension in further empirical studies from various aspects and to greater extents. This study provides suggestions for the recognition of the interaction between different affective, and cognitive influential factors in the multidimensional reading process, as well as a basis for the teachers' and linguists' methodology with respect to learners in terms of their individual differences while instructing reading comprehension in German as a foreign language.