For predicting the strength of fibre-reinforced metal matrix composites, the in situ fibre strength value has to be introduced in the calculations. Tension tests series have been conducted on SIC fibres (SCS0 and SCS2 TEXTRON) before and after chemical interaction with a pure liquid aluminium bath and the reacted fibres have been tested before and after dissolution of the aluminium coating simulating the metallic matrix around the fibres. The results obtained for the different fibre batches show that the in situ fibre resistance may differ significantly from the strength of as-received or extracted fibres that is usually adopted in the models.