The present study was conducted to identify causal relations of intellectual capital indices in Shahid Tondgouyan Petrochemical Company using a multiple criteria decision making approach. A conceptual model including five indices and 22 subcriteria (adapted from the model proposed by Chander Sehar et al., in Procedia Soc Behav Sci 189:275-284, 2015) was developed and modified according to comments of seventeen experts. Results of data analysis using the DEMATEL technique via visual basic coding indicated that human capital has the highest influence on other elements, followed by customer capital. Moreover, human capital and customer capital are two causes, whereas communication capital, structural capital and innovation are the effects. The results obtained in this research can be regarded as a guidance and complementation for improving intellectual capital management.