With the exponential development of e-commerce in recent years, there is an emerging demand for effective negotiation support tools. This paper addresses the possible influence of culture and explanation facility on negotiation performance involving negotiation agents in an e-commerce context. Explanation facility, an important element of knowledge-based systems, has been well recognized for its benefits. When incorporated into negotiation agents, it is expected to improve the performance of negotiators. Also of interest here is culture. Certain moderating effects due to cultural differences are anticipated, in that the relationships between explanation facility and negotiation outcomes are conjectured to be contingent upon cultural conditions. This paper puts forth several hypotheses for experimental investigation. Preliminary results of a study are presented.