This paper attempts to shed light on the role of trust and service quality on relationship quality. Building long-term and high quality inter-firm relationships is imperative for efficient and effective management of disribution channels. The study focuses on the relative effects of two critical factors on assessments of relationship quality in conventional distribution channels, namely, perceived service quality of the exchange partner and degree of -affective and cognitive-trust placed in the exchange partner. Data were collected from a random sample of 458 firms operating in two big cities of Turkey through questionnaires. Findings of regressions indicate that cognitive trust, affective trust and service quality have a positive and strong impact on relationship quality, independently from each other.