Port systems are influenced by arrival patterns of ships, quay configurations, cargo handling conditions, storage capacity, connections with inland transport, environmental conditions and various other aspects. The extent to which these aspects effect port operations can be determined by empirical "rules of thumb", queuing theory and simulation models. Simulation models are especially suitable for the analysis of complex port systems. The objective of this thesis project was to produce a simulation model for a port system. Originally this was a group of terminals at the port of Kaohsiung, Taiwan. Secondly, the model was supposed to be applicable to other ports without extensive adjustments. The model, which has been created, provides a framework to perform a simulation of port operations for port design purposes. The flexibility of the model proved useful when the application of the model was switched to Pontianak in Indonesia. The model describes a port for which the user can define the number of terminals, berths, cranes, gangs, shifts, cargo-commodities and arriving shipclasses. After a ship has been generated, it follows a route through the port system, starting at the anchorage, sailing to a berth, mooring at a quay, being loaded and discharged and leaving the port. The arrival of a ship creates an incoming and outgoing flow of cargo with inland transport and a requirement for storage area. Port operations can be restricted by several circumstances (tidal window, bad weather, strikes, absence of shifts or inland transport in weekends, breakdowns of cranes). The Main Public Port at Pontianak is a terminal with five quays (totallength 507 m) at which annually 620,000 tons of general and bagged cargo are handled. This throughput is expected to increase to 1,280,000 tons in 2002. In view of the already high berth occupancies at present, it is expected that extensions and adaptions of the port facilities are required. The occurrence of congestion for the current configuration has been examined with the use of the simulation model. Several combinations of quay length increasement and cargo handling rate improvement have been tested, for the 2002 throughput forecast and for four fluctuations of the forecast. The results of the simulations have been compared to a quay configuration, which is proposed by a previous port development study ('Feasibility Study and Masterplan Review for Pontianak Port Development' by HASKONING Royal Dutch Consulting Engineers and Architects and PT Delta Marga Kreasi, August - December '92) and has been calculated with the queuing theory. Some critical remarks with regard to the proposed configuration are made. One other preferabie configuration is pointed out. Comparisons between combinations of quay length increasement and cargo handling rate improvement are performed with data for vessel performances (waiting and service times) and rates of berth occupation and storage area utilization.