Modification of BaBi8Ti7O27 ceramics was investigated by La substitution for Bi, and the dielectric properties were determined together with the microstructures. Ba(Bi1-xLax)(8)Ti7O27 solid solution was observed for x less than or equal to 0.25, and Ba(Bi,La)(2)Ti4O12 secondary phase appeared for x > 0.25. The dielectric constant, the dielectric loss and the temperature coefficient of dielectric constant increased first and reached their maximums at x = 0.15 then decreased together. Ceramics with good dielectric properties: epsilon = 102, tan delta = 0.0006 and tau(c) =-152 ppm/ degreesC at 1 MHz were obtained at x = 0.5 where the ceramics were not single phase. (C) 2002 Elsevier Science Ltd. All rights reserved.