Not now, no - rules for Hydrangea are to wait till about April,
as new growth starts appearing, and then you remove this year's spent flowerheads and stems, and any dead wood.

Sorry Bamboo, but H. paniculata is pruned in February and you may, if you so choose, cut it right to the ground. That depends on how big a shrub you want. H. paniculata types flower on new wood, so the more new stuff you encourage by pruning in February, the more flowers you will get.
This is the complete opposite to H. macrophylla which are pruned as Bamboo suggests.

Oh thank goodness, Owdboggy - I remember a question from someone in US recently on a Hydrangea, when I discovered it could be cut now - but I'll be damned if I could remember whether it was paniculata or not. I stand corrected, and will now write that name down so I don't forget again... Question though Owdboggy, can it be cut right now, rather than waiting till February, as the woman in America does - or was that a different Hydrangea. Wish I could find the question again...

I suppose it could be pruned now, but the advice given in my books on Hydrangeas is to prune in February as the old stems protect the crown from frost etc. If I was going to prune now I would be very much inclined to put a good thick mulch over the top.

Thanks - it must be that one the American lady was speaking of - its such a pity we can't save questions to favourites... I might PM tugbrethil, I recall his being involved in the query too.

Thanks to you all. I will prune in February and hope for the best!