The variations in the number of intense tropical cyclones with maximum sustained (1 min) surface winds of 100 knots and more is investigated over the last thirty years (1969-1970/ 1998-1999) in the south-west Indian Ocean east of 90°E. The intensity of cyclones has been estimated through the interpretation of satellite pictures. A comparison is made with the data given by the Joint Typhoon Warning Center and those reported by Meteo-France Reunion for the 1984-1985/1998-1999 period. This study shows that an annual average of three intense cyclones formed in the south-west Indian Ocean. The analysis over the three past decades indicates that the number of intense cyclones has a tendency to increase ; this is especially the case of the extreme cyclones (120 knots and more) for which a stronger increase in frequency occurred in the 1990s. This increase is not steady : a light decrease in the number of intense cyclones took place over the 1980-1989 decade. It is however remarkable that the ENSO which occurred in the 1980s were accompagnied by no intense cyclones. And only one intense cyclone formed during the 1997-1998 El Nino. The 1990-1999 decade constitutes the one for which the greatest number of intense cyclones has been observed since the data exists. The monthly distribution of intense cyclones shows that 16% occurred at the beginning of the season (November and December), 51% during the full season (January and February), and 33% at the end of the season (March and April). Considering the extreme cyclones, the figures are 24%, 35%, and 41%, respectively. Physical mechanisms are exposed to attempt to explain these variations.