The empirical literature that relies on conventional cointegration approaches fails to support the existence of cointegration between exports and imports in some countries. This article moves a step ahead and contributes to existing literature to overcome the issue of the unexplained relationship between exports and imports. The research samples consist of quarterly data over the periods 2000q1-2017q2 and 2004q1-2017q2 for the Croatian and the Serbian cases, respectively. The results illustrated that the statespace model with time-varying parameters (T.V.P.) is well suited to establish the relationship between exports and imports when the standard cointegrating relationship does not hold.