In this research, it was aimed to determine the deficiencies of secondary school fifth- and sixth-grade students on word problem solving and their failures in this process. For this purpose, four separate word problems were asked to the students and their written answers were taken at the implementation process. The analysis of the data suggests that a significant part of these secondary school students had deficiencies during word problem solving and their failures in this process. Moreover, these deficiencies and failures were reported to be related to the understanding of word problems and the planning for solutions in the solving process. In addition, it was found that the fifth- and sixth- grade students rarely attempted to use drawing in order to solve the word problems. They mostly had deficiencies in deciding which arithmetic operations to be used while approaching the problems and they had failures at their arithmetic operations.