Complaints against Channel 5's Naked Jungle, presented in the nude by Keith Chegwin and with naked contestants, were rejected by the Independent Television Commission.
The one-off show caused controversy when it went out as part of a naturism week in June and led Culture Secretary Chris Smith to question the quality of British TV.
Thirteen complaints from viewers who criticised the show on the grounds of taste and decency were dismissed by the ITC.
The programme gave a huge ratings boost to Channel 5 despite its late-night slot.
Nudity 'clearly signposted'
The TV watchdog said the show did not break its programme code because it was broadcast well after the watershed and the nature of its content was "clearly signposted to viewers in advance".
Chegwin - wearing just a pith helmet - guided male and female contestants through a series of puzzles in a jungle environment.
The tasks included tests such as the Pool of Death and Waterfall of Venus.
The show sparked a debate in parliament but Channel 5 argued that the show was trying to escape the Victorian attitude to public nudity as sordid.
The ITC rejected further complaints about a season of naturist programmes screened by the channel.
Viewers complained that nudity should not have been shown in the series Stark Naked before the 2100 watershed.
But the ITC said there was no absolute bar if it was "defensible in context".
In the same monthly bulletin, the ITC upheld complaints against Channel 4 for a spoof interview with former Rolling Stone Bill Wyman.
Wyman complained after he was duped into appearing in the interview for the Candid Camera-style Trigger Happy TV.
The ITC said the station had broken programme rules "by its failure to secure permission for the set-up interview".
Wyman was not named in the TV regulator's report after he asked not to be identified.
However, he has previously given an interview to Q magazine discussing his treatment.