Pruning raspberry bushes improves their overall health and vigor. In addition, when you prune raspberry plants, it helps increase fruit production. Since raspberries grow only foliage the first season (year) and flowers and fruit the next (second year), removing dead canes can make it easier to obtain a maximum yield and berry size.
How and when to prune raspberries depends on the type you are growing.

You have Summer and autum bearing ?

Summer fruiting raspberries 'should' have finished fruiting by now and the cane that grew this year can be cut down, I'd also keep the new canes cut back to about 5 foot and tie them into the support wires. Autumn fruiting rasps. will be fruiting now and the canes are cut down to about 6 inches in February or early March.

Wow, got the hang of this now. Thanks for the help with the raspberries. I have had about 12 in the summer, but there are new green ones growing on the branches now, so I guess it could be one of the late fruiting types. I will wait a while longer before pruning in order to see whether they come to anything. Thanks again everybody

There is no hurry to cut back autumn fruiters. You can wait until all the leaves have fallen off if you want to. Mine are only just beginning to fruit - a bit late this year. They fruit on the current years canes so are cut back completely to the ground.

The summer fruiters can be cut back now if you haven't done it already but don't cut off the canes that grew new this year as those are the ones that will fruit next year.

Good luck and come back if you need more info.

Sorry MG, I didn't notice your reply to this question.

No problem Stera!