A formalin inactivated alum gel adjuvated combined vaccine of bovine rotavirus (BRV), bovine coronavirus (BCV) and K99 enterotoxi­genic Escherichia coil (ETEC) was prepared and evaluated. Ten suscepti­ble calves were vaccinated intramuscularly twice 2 weeks apart using 2 ml/calf. The vaccine was tested for safety in calves and mice and for sterility. Sera of immunized calves showed high antibody levels (4-8 log2 for both BRV and BCV) using serum neutralization test. The ELISA anti­body titres were also satisfactory high for the three vaccine compo­nents. Passive mouse protection test revealed 80-100% protection agai­nst K99 ETEC component. The microagglutination test was also used for evaluation of the potency of K99 ETEC and the titres obtained reached 320 and 1810 at 2 and 8 weeks postvaccination, respectively. It is recommended to prepare the trivalent vaccine locally for control of diarrhoea in calves.