abstract objectives gradual increase length and complexity of utterance (gilcu) therapy method is a form of operant conditioning. this type of treatment is very precise and controlled that is done in 54 steps in 3 speech situations consisted of monologue, reading and conversation. this study aimed to examine the effects of gilcu treatment method on reduction of speech dysfluency of school-aged children with stuttering. methods in this quasi-experimental study, 32 children with stuttering 6-11 years old were selected from referred to speech therapy clinics using convenience sampling. then, they were assigned into two groups. the first group was treated by gilcu therapy method by researcher and the second group by traditional methods by another speech therapist. both groups had fourteen 45-minute sessions that conducted one to two times per week. pre-test and post-test of both groups was assessed using the ssi-3 scores. the obtained data were analyzed using the kolmogorov-smirnov ,t-test, and covariance test. results both groups had statistically significant difference (p<0.005) in the stuttered syllables frequency, the average of moments of stuttering from maximum moments of stuttering and physical activity was examined just according to speech situations such as reading and conversation. first group (receiving gilcu therapy method) in comparison with traditional method did not show significance improvement statistically (p>0.005) with respect to parameters of ssi-3 scores. discussion these results suggest that a non programming treatment for stuttering may be effective with school-aged children who stutter.