The work examines the dependence of the legal consequences of a transaction on suspensive and dispensatory conditions. The problems of distinguishing between a dispositive condition and non-fulfillment of an obligation are considered, and the question of whether the action of a party to a transaction can constitute a suspensive or dispensable condition is examined. The content of the legal relationship in the period before the occurrence of the condition is considered. The methods of protecting the rights and legitimate interests of the parties to a conditional transaction are characterized. The range of transactions that cannot be concluded under a condition is outlined. The suspensive and severable conditions of testamentary dispositions are examined in detail. The features of the suspensive and severable conditions of individual agreements are revealed, in particular - a purchase and sale agreement, a gift agreement, a lease agreement, a simple partnership agreement. When distinguishing the concepts of “suspensive condition” and reservation of property rights, the doctrine of the German doctrine on an administrative transaction under a suspensive condition is analyzed.