What group and variety are they, Andy? Most of the plants sold under the name "Rhododendron" are supposed to be evergreen, but there is a group of Rhododendron species and hybrids that are sold as "Azaleas", and a large minority of those are deciduous.

Varietal names of your plants would be very helpful, but it would also be useful to know whether or not you're growing them in pots, how long you've had them. If you've any photos showing them in flower, it would be good to see those, especially if you don't know what varieties they are.

thank you so much for replying, I appreciate that, I have put them in big pots , had them two months, as they were birthday presents, the variety is Praecox, dwarf. They have not flowered yet with me, but they do have new flower buds forming. The plants look healthy, about 60% leaves fallen off, the rest are green. I have kept them well watered,not standing in water. Thanks for your help, I am not sure how to send a photo!!

Andy

Rh. praecox is a small leafed species of rhododendron which will flower early in the year. We have some in the garden. They are generally sold as being 'evergreen' but this is not totaly correct as, over the winter they will lose some leaves. However, 60% leaf loss at the start of the winter is excessive, to be polite. Firstly, they are definitely not a house plant so I hope that they are in the cooler outdoor climate. They require an acid soil so did you fill the pots with ericaceous compost and, if so, did it just come straight out of the bag? The compost should be well drained so should have extra grit or coarse sand added to prevent it holding excessive water, particularly in winter. Do you water with tap water and, if so, is it considered 'hard', ie do you get scale in the kettle. These plants require a soft, acid water which is most easily obtained by collecting and using rainwater. I believe that you can get rid of the lime by boiling the tap water and then allowing it to go cold but it is not something that I have to deal with.
Rh. praecox will start flowering in Feb/March in our garden but could be even earlier for you. The flower buds don't particularly like frost so keep the pots close to the house wall and in a position that the early morning sun does not hit them.
A further thought, Andy, when you took the plants out of the pot they cames in were the roots in a hard, tight knot. If so, they should have been gently teased appart to allow them to spread out in their new home.
Good luck with them and I hope you get a good show later in the winter.