An experiment was conducted at the Horticulture Farm of the Bangladesh Agricultural University, Mymensingh during the period from August, 2001 to March, 2002. It was carried out in split plot design with three replications. Four levels of nitrogen and four levels of potassium were used in the study. The objectives of the study were to evaluate the effects of N and K nutrition on growth and yield of autumn grown onions. The results of the experiment revealed that both N and K showed significant effects on all the parameters studied. The application of 110 kg N and 150 kg K per hectare produced the highest bulb yield (11.25 t/ha) in cv. Taherpuri which was statistically identical with the combinations N70 X K150, N90 X K90, N90 X K150, N110 X K90. But from overall considerations, the treatment combination of N90 X K90 was found to be the best.