In order to study the effect ofsome growth regulators treatments on callus growth as affected with the interaction between three different temperatures (18, 23, 28^oC + 2^oC), photoperiod, type of explants and incubation period. Three experiments were carried out during the two successive years 2001 and 2002. The results indicated that, the interaction between the different treatments led to significant difference in callus growth when incubation at different temperature degrees (18, 23 and 28^oC). The suitable temperature degree for growth of echinacea explants was 23^oC. Culturing the explant under the light condition encouraged the callus growth in light than dark.     The explants under investigation recorded significant difference in callus growth and the cotyledonary leaf explant was the best one. The first treatment activated the callus growth significantly than the second and third treatments. In addition, significant increment was achieved in callus growth with increasing incubation period, and the best incubation period for callus growth was 35 day.     The interaction between different treatments showed that the callus growth was increasing significantly with increasing the incubation period even with different growth regulators treatments, explant type, photoperiod, and different temperature degrees (18, 23, and 28^oC).     As for the interaction between factors controlling callus establishment, it is clear that the most convenient conditions on the optimum growth of echinacea callus tissues are application of cotyledonary leaf explant, MS basal medium supplemented with BA 1.5 mg/L + NAA 1 mg/L & BA 2 mg/L + NAA 1 mg/L and light condition for 16 hr./day photoperiod at intensity of 6000 Lux, at 23^oC for 35 day incubation period.