Were tested treatments to break seed dormancy in Cassia bicapsularis L., C. javanica L. and C. speciosa Schrad. Were evaluated the percentage and the speed of seedling emergency in sand placed in plastic box. The treatments were immersion in concentrated sulphuric acid for 1, 2 and 3 hours; immersion in boiling water for 8, 12 and 24 hours in the sarne water out of boiling; manual scarification and control. The results showed that the immersion in sulphuric acid for 2 hours and the manual scarification were the best treatments for the three studied species. The immersion in sulphuric acid for 1 hour was also efficient for C. bicapsularis and for 3 hours for C. javanica.