The Harvard multi-room fire simulation has been used to simulate a fire in a single-level, 8 room complex. The model has been enriched to simulate forced ventilation and re-dimensioned to allow up to 10 rooms and 20 vents. No experimental, full-scale fire data is available against which to compare the predictions. Comparative results are provided which illustrate the effect of no forced ventilation and forced ventilation providing up to six air changes per hour. The forced ventilation supplied air to rooms opening off a corridor and extracted it from the corridor ceiling. For one large room, supply was at floor level and extraction from the ceiling. With this arrangement, the spread of fire gases was inhibited and tenability times increased by the forced ventilation. With another supply and exhaust arrangement the reverse might have been expected.