Generally, the economic health of Swedish roundwood truck transport companies has not been good. Profitability is important for maintaining the stability in the transport business, which is a condition for long-term transport planning in the forestry sector. The scope of this study was to identify probable factors influencing the profitability of roundwood truck transport companies and quantify the influence of these factors on economic results. The study was carried out at a major roundwood truck transport organisation in mid-Sweden and was implemented in four steps. In the first step economic results from the haulage contractors were collected and a random sample was taken from accounted net margin for the account year 2005/2006. In the second step hauliers were interviewed to identify probable success factors. At the third step data for identified factors were gathered through a questionnaire.