Inter-organizational relationships are studied in three dimensions including relational structural, and outcome. The main objective of this research is to study the relationships between relational factors and their impact on the forming of structures. Therefore, via defining operational variables for power, risk perception, control and trust, as relational variables, the impacts of these variables on collaborative structures were investigated. The relationships between these variables, in the form of some hypotheses and a conceptual model, were examined using a sample including 112 high ranked managers. The results indicated that unbalanced power has a positive effect on relational risk perception. Relational risk perception itself is a positive predictor for safeguard control and a negative predictor for commitment-based trust. On the other hand, safeguard control is a negative predictor for collaborative structure while commitment-based trust is a positive predictor for such kind of structures. Further investigation revealed that commitment-based trust does not have a significant effect on collaborative structure while it has passed a threshold, and safeguard control does not have a negative effect on collaborative structure while it has not passed a threshold.