When does this happen? Are they newly planted ones, or older ones? Have you checked for aphids?

Also, are the older leaves going a bright chrome yellow, or are the newer ones coming out chartreuse with green veins? Are dark spots or brown tips or edges visible? "The diagnosis is in the details"

As you'll have gathered, we need more info, so I'll add some questions
1. How long have you had the roses?
2. In the ground or in pots?
3. Have you pruned and fed them this year?
4. Have you sprayed with fungicide/aphid treatments?

Marina, in case you are wondering, you can answer the same way we do--by writing in the white space just above the green "Add comment" button.