Links of balancing and cobalancing numbers with Pell and associated Pell numbers are established. It is proved that the n th balancing number is product of the n th Pell number and the n th associated Pell number. It is further observed that the sequences of balancing and cobalancing numbers are very closely related to the Pell sequence whereas, the sequences of Lucas-balancing and Lucas-cobalancing numbers constitute the associated Pell sequence. The solutions of some Diophantine equations including Pythagorean and Pythagorean-type equations are obtained in terms of these numbers. 1.