The present study was carried out to investigate the varying pattern of rotavirus electropherotypes in Delhi, India. During a 25-month study period, rotavirus was detected in 104 of 990 (10.5%) samples collected from children with acute gastroenteritis, except in the months of June 1988, June 1989, October 1989, January 1990 and March 1990. Viral RNA migration was studied by PAGE in 83 rotavirus positive samples, and 69 (83.1%) of them gave a discernible RNA pattern. A "long" RNA pattern was observed in 58 (84%) and a "short" RNA pattern in 11 (16%) samples. There were three major electropherotypes among the "long" RNA types and two major electropherotypes among the "short" RNA RNA types. Sequential appearance of electropherotypes was seen with every seasonal peak of infection.