They both beat medical problems to become Otago's stars at the New Zealand athletics championships at Auckland.
O'Shea (24) caught the flu, was put on a dose of antibiotic medicine, and was only able to do four training sessions in the last three weeks.
Whyte (19) has suffered from chronic muscular problems and has raced only sparingly over the summer months.
They have been nursed carefully by their coach Brent Ward and they both rose to the occasion with superb efforts in the senior men's events at Auckland.
They both qualified for the World University Games at Kazan, Russia, in July.
O'Shea won the gold medal in the 400m hurdles in 50.64sec and Whyte when he won the flat 400m in 46.52sec.
My race didn't go to plan,'' O'Shea said.
''I took extra strides between the hurdles in the first 200m and clipped a couple of hurdles.''
O'Shea was disappointed in his third place in the flat 400m on Saturday and was over-aggressive when he attacked the hurdles yesterday.
''I was very relieved to get a personal best time like that,'' he said.
''Once I get my rhythm and stride pattern working, I knowI can go faster.''
O'Shea was just 0.16sec slower than the Otago record of 50.48sec that Roger Johnson ran at the Munich Olympic Games in 1972.
Whyte ran a steady race before he quickened the pace around the top bend and came home fast down the straight to pass Cameron French (Waikato-Bay of Plenty). French was timed at 47.23sec and O'Shea was third in 47.48sec.
It was a significant win for Whyte who won the junior men's title last year. He also came second in the 200m behind the 100m champion Joseph Millar (Waikato-Bay of Plenty), in 22.15sec.
O'Shea and Whyte will be looking for Otago records when they race in the Australian championships on the fast Olympic Games track at Sydney in two weeks.
The pair were members of the Otago 4 x 400m relay team that won the gold medal in 3min 15.43sec. The other team members were Stephen Isaac and Ben Anderson.
Rozie Robinson completed the senior women's walking double for the third year in a row, when she won the 20km road walk in 1hr 47min 42sec. She beat Te Anau's Lesley Cantwell (Southland) by 3min 44sec.
Holly Robinson won a gold medal in the AWD shot put with 10.07m.
She qualified for the world Paralympics championships in France in July when she came sixth in the women's 20 javelin with 32.62m.
Her training partner Rory McSweeney also qualified for the world championships when he came fourth in the open men's javelin with 46.26m.
Christina Ashton (15) won the women's 18 100m hurdles in 14.63sec. She broke the Otago women's aged 15 record with her heat time of 14.87sec and lowered it again in the final.
Robert Jopp in the 400m (48.50sec) and Sam Bremer in the 5000m (15min 22.42sec) won men's 20 titles.
Otago athletes won 27 medals - nine gold, eight silver and 10 bronze - in the three-day championships. Last year, Otago athletes won 22 medals - eight gold, three silver and 11 bronze.
NZ championships
Otago's champions
Rozie Robinson, Sam Bremer, Christina Ashton, Holly Robinson, Andrew Whyte, Robert Jopp, Daniel O'Shea, Stephen Isaac, Ben Anderson.
